solid-phase organic synthesis and catalysis: some recent

Hindawi Publishing CorporationJournal of CatalystsVolume 2013 Article ID 614829 20 pageshttpdxdoiorg1011552013614829

Review ArticleSolid-Phase Organic Synthesis and Catalysis Some RecentStrategies Using Alumina Silica and Polyionic Resins

Basudeb Basu and Susmita Paul

Department of Chemistry University of North Bengal Darjeeling 734 013 India

Correspondence should be addressed to Basudeb Basu basu nbuhotmailcom

Received 26 February 2013 Accepted 7 July 2013

Academic Editor Raghunath V Chaudhari

Copyright copy 2013 B Basu and S Paul This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Solid-phase organic synthesis (SPOS) and catalysis have gained impetus after the seminal discovery of Merrifieldrsquos solid-phasepeptide synthesis and also because of wide applicability in combinatorial and high throughput chemistry A large number of organicinorganic or organic-inorganic hybrid materials have been employed as polymeric solid supports to promote or catalyze variousorganic reactionsThis review article provides a concise account on our approaches involving the use of (i) alumina or silica eitherhaving doped with metal salts or directly and (ii) polyionic resins to either promote various organic reactions or to immobilizereagentsmetal catalysts for subsequent use in hydrogenation and cross-coupling reactions The reaction parameters scopes andlimitations particularly in the context of green chemistry have been highlighted with pertinent approaches by other groups

1 Introduction

The concept of solid-phase organic synthesis (SPOS) datesback mid-1940s and the solid-phase peptide synthesis in1960s developed byMerrifield has been a pioneeringwork [1]Over the last two decades there has been a surge generatingtremendous interest in expanding this field of solid-phasesynthesis [2ndash10] There is a clear emphasis in syntheticchemistry towards developing environmentally friendly andsustainable routes to a myriad of materials The emphasisis most apparent in the growth of green chemistry [11ndash14] According to Paul Anastasmdashone of the founders of theconcepts of green chemistry ldquoCatalysis is a foundational stoneof Green Chemistryrdquo [11 12] One important aspect of cleantechnology is the usage of environmentally friendly surfacecatalysts typically a solid catalyst that can be easily recoveredwhen the reaction is complete [15] Polymer supports playa critical role in combinatorial chemistry and consequentlysolid-phase organic synthesis continues to grow in impor-tance [16ndash23] One of the major advantages of this techniquethat has attracted attention of the chemists is the cleanisolation of the products by simple filtration As a resultthis technique has become a valuable tool in combinatorialchemistry and high throughput chemistry an integral part

of drug discovery and research [24ndash26] The solid-phaseorganic synthesis of small organic molecules depends largelyon the adaptation of solution reactions to solid phase [27]Alternative synthetic routes that avoid need of any toxicsolvents and reduce the number of steps with high atomeconomy and energy efficiency are some of the key features ofgreen chemistry On the other hand good dispersion of theactive reagent sites involving high selectivity easier work-upand improved efficiency are attractive features for solid-phasetechnology

Both inorganic and organic polymers have been em-ployed to mediate or promote organic reactions [28ndash30] Asregards use of inorganic oxides silica and modified silicaalumina zeolites clays and so forth have found wide appli-cations in promoting various organic reactions in solutionphase or in solvent-free conditions [31ndash38] On the otherhand organic polymers such as polystyrene (PS) or that par-tially crosslinked with divinylbenzene (DVB) have remainedthe major choice besides uses of some other dendrimers [39ndash50]The choice of solid phase polymers with suitable linkersthe nature of binding with the substratereagent (covalent ornoncovalent) stability and recyclability have remained someof the salient points for successful and efficient solid-phasesynthetic protocol

2 Journal of Catalysts

Inorganic oxidesandor doped

inorganic oxide

KF-alumina

Silica orFe(III)-silica

Pd-catalyzed

Pd-catalyzed

alkylations

S-acylation

Quinoxaline synthesis

Aza-Michaeladdition

Selective benzimidazole

synthesis

CndashC couplings

CndashN coupling

N- or S-

Figure 1

Towards developing new organic reactions and catalysisour group has primarily employed two categories of poly-mers (i) inorganic oxides either directly or having dopedwith some other inorganic salts and (ii) polyionic resinsto immobilize reagentsmetal nanoparticles (NPs) as thesolid-phase catalysts or heterogeneous nanocatalysts Thisreview article will primarily focus on our efforts vis-a-vismentioning notable and relevant achievements from otherresearch groups The subject has been organized accordingto nature of the target molecules to synthesize nature ofreaction and also the type of solid supports employed invarious reactions

Figure 1 illustrates examples of our efforts towards thesynthesis of CndashC and CndashX (heteroatom) bond-formingreactions and synthesis of libraries of small heterocyclicmolecules of biological importance having promoted orcatalyzed on commercially available silica gel alumina ordoped with iron(III) salt or potassium fluoride respectively

2 KFAlumina MediatedCatalyzedOrganic Reactions

Commercially available alumina (Al2O3) is known to catalyze

or promote a variety of organic transformations [2 51] How-ever alumina doped with potassium fluoride (KFalumina)has been extensively used as solid basic surface in vast rangeof organic transformation [52] since it was introduced byAndo et al [53ndash56] Alumina doped with KF can ionizeC-acids up to pKa sim35 [57] Although the actual basicsite developed on the surface on alumina is dependent oftemperature and partially debatable the 19F magic angleNMR and IR spectroscopic measurements have shown thatthe fluoride anion species inKFalumina ismore electron richthan fluoride anion in pure solid The conditions of loadingof KF seem to be critical to its functioning and displayingvarying properties

21 Buchwald-Hartwig CndashN Cross-Coupling Reaction Thefirst reaction was studied on the surface of KFalumina is theBuchwald-Hartwig CndashN cross-coupling reactions betweenaryl halides and an amine Initial independent reports by

Buchwald and Hartwig clearly noticed that the success ofsuch coupling is tricky to the use of the base and sodium orpotassium tert-butoxide was found to be best for such CndashNcross-coupling reactions [58ndash61] Secondly initial conditionswere not successful for heteroaryl substrates possibly becauseof formation of stable palladium complex that does notfurther participate in the catalytic cycle Buchwald howevercircumvented this problem by using chelating ligands so asto avoid formation of substrate-based palladium complexes[62]

Palladium-catalyzed CndashN hetero cross-coupling reac-tions between bromopyridines and amines (both primaryand secondary) can be efficiently performed on aKFalumina(basic) surface (Scheme 1) thus negating the use of strongbases such as sodium tert-butoxide The reaction conditionshave been optimized with reference to catalytic systemssolvents and the surface A variety of phosphines both asmono- and bisphosphine ligands are found to be equallyactive [63]

To broaden the scope of this CndashN hetero cross-couplingthe reaction protocol has been extended to haloaromaticsThe reactions are not only found to be applicable to bro-moarenes but also offer high selectivity in cross-coupling ofpolyhaloaromatics Indeed there has been high selectivitybetween mono- or polyaminations (bis- tris- or tetra-)depending on the proportion of KF and alumina [64] Higherproportion of KF and slight higher temperature can lead topolyamination while lower amount of KF in KFaluminagenerally affords only monoaminated product (Scheme 2)

Notable features of the use of KF doped with alumina(KFalumina) are (i) the use of NaOBu119905 can be avoided(ii) conditions are not ligand-specific (iii) solvent-free reac-tions generally give better yields (iv) applicable to bothbromoarenes and N-heteroaryl bromides (v) varying pro-portions of KF per gram of alumina offer selectivity and (vi)recycling of the solid surface is possible

22 DoubleMichael Addition TheMichael addition reactionan important CndashC bond-forming reaction is known to pro-duce adducts which have found wide synthetic applications[65ndash68] Several acidic and basic catalysts are used to affectthis conjugate addition reaction Side reactions frequentlyencountered in the presence of a base catalyst are secondarycondensations polymerizations and double additions How-ever the reactions in which two CndashC bonds are selectivelyformed by intermolecular and consecutive double Michaelreactions in one-pot are very rare It was observed thatKFalumina can promote consecutive Michael additions ofthe nucleophile derived from acetophenone to electron defi-cient alkenes Thus an efficient and highly selective one-potprocedure for the double Michael reactions was developedleading to the formation of pimelate ester derivatives [69]This is the first example of selective double Michael additionsof aromatic and aliphaticmethyl ketones to electron-deficientalkenes mediated over KFalumina (Scheme 3)

Both aliphatic and aromatic ketones underwent bis-addition with similar efficiencies and afforded the desiredproducts Mixture of acetone and ethyl acrylate yielded the

Journal of Catalysts 3

N

Br

X

X = H Br alkyl

Pd catligand

KFalumina (14)+

N

X

N O

O+

Br

N

N O

OR R

LigandKFalumina

R2NHor

RNH2

NHR or NR2

(48ndash91)

(62ndash73)

Pd(OAc)2 or Pd2(dba)3 HndashN

X = H NR2 alkyl

Scheme 1

Br

Brn

Brn

+

n

NR2

NR2

Pd2 (dba)3-BINAP Pd2 (dba)3-BINAP

n = 1 2 3

R2NH

(gt80) (70ndash85)

NR2

KFalumina (32)135∘C KFalumina (23)80∘C

Scheme 2

OCOOEt KFalumina

O

COOEt

COOEt

O

COOEt

67 8

CH3

50∘C 10 h

+ +

OCOOEt KFalumina

O

COOEt

COOEt63

+CH3H3C 40∘C 12 h H3C

Ph KFalumina

75

O O Ph

+CH3

CO2CH3 CO2CH360∘C12 h

Scheme 3

corresponding bis-adduct diethyl 3-acetyl-heptanedioate in63 yield keeping the other methyl group intact Whiletesting similar reactions using methyl crotonate or methylcinnamate as the Michael acceptors the reaction ended upselectively with the formation of monoadducts only evenafter prolonged reaction time and elevated temperaturesThepossible reason of reluctance to undergo double additionsmay be attributed to the steric inhibition at the 120573-carbon ofthe conjugated olefinsThiswas further corroboratedwith theresult that the double Michael adduct was indeed formed in72 yield with methyl methacrylate

23 Suzuki Coupling Reaction Biaryls and higher homo-logues are an important class of conjugated polyaromaticcompounds originating from benzene as unique buildingblocks Polyaryls have found wide range of applications

as liquid crystals laser-dyes and conducting polymers Inaddition biaryls and higher homologues are often presentas subunits in numerous biologically active natural productspharmaceuticals and agrochemicals [70ndash80] An efficientpalladium-catalyzed cross-coupling of polyhaloaromaticswith arylboronic acids on KFalumina was developed undermicrowave-assisted condition (Scheme 4) [81] The resultshave expanded the scope of the Suzuki reaction on a solvent-free inorganic surface leading to the synthesis of a largevariety of polyaromatics The reaction is fast operationallysimple and allows rapid access to a variety of polyaromatichydrocarbons

24 119873-Arylation of Amines An experimentally simplemicrowave-assisted solvent-free N-arylation of primaryamines with sodium tetraphenylborate or arylboronic acids


Xn

+KFaluminasolvent-free

MW

n

X XX = Br or I

B(OH)2Pd Cat (2 mol)

(58ndash90)n = 1ndash3

Scheme 4

promoted by inexpensive cupric acetate on the surfaceof KFalumina has been developed (Scheme 5) [82] Thereaction is selective for mono-N-arylation and a variety offunctional groups are tolerated in the process establishing theversatility of KFalumina

Primary amines were monoarylated successfully usingeither sodium tetraphenylborate or arylboronic acids Aro-matic amines bearing either electron-donating or electron-withdrawing groups gave the corresponding unsymmetricaldiarylamines in good to excellent yields Aliphatic primaryamines and benzylamine also produced N-arylated productsin 70ndash75 yields Halo-substitutions either on the arylamine or the arylboronic acid remained unaffected under thereaction conditions

25 Synthesis of Quinoxalines Functionalized quinoxalinesrepresent a privileged class of N-containing heterocycles andexhibit a wide range of biological activities including antivi-ral antibacterial anthelmintic anti-inflammatory kinaseinhibitory and anticancer activities [83ndash89] A facile andexpeditious solid-phase synthesis of libraries of quinoxalinespromoted on KFalumina surface via tandem oxidation-condensation or condensation reactions has been developed(Scheme 6) [90] The reaction protocol is operationallysimple and mild Moreover solvent-free reaction conditionmakes the reaction procedure eco-friendly and economicallyviable The methodology has been established as a direct andexpeditious process of preparation of functionalized quinox-alines from different substrates like 120572-hydroxy ketones 120572-bromoketones or 120572-dicarbonyl compounds using a hetero-geneous basic surface of KFalumina

3 Reactions Promoted by Silica Gel

Silica gel is nontoxic nonflammable nonreactive and stablewith ordinary usage In chemistry silica gel is used inchromatography as a stationary phase [91] Owing to itshighly developed surface (5ndash800m2 gminus1) and high porosityit is used as sorbent for dehydration of gases and fluid asa catalyst support for various reactions Chemical reactionscatalyzed or promoted by silica gel usually proceed undermild conditions and with high chemo- regio- and stereo-selectivity and are operationally simple In the quest ofdeveloping solid surface mediated organic reactions a fewreactions are described using silica gel as a potential surface

31 Hetero-Michael Conjugate Additions 120573-Amino ester andits derivatives are attractive targets for chemical synthesisof products with a wide range of biological activities and

KFaluminaMW

Ph4BNaor

PhB(OH)2R1NH2

Cu(OAC)2

R1 = Alkyl or aryl

NHR1

+

Scheme 5

pharmacological properties [92ndash94] 120573-Amino esters areuseful intermediates in certain attractive syntheses of 120573-lactam antibiotics [95ndash97] Optically active 120573-amino estersand derivatives often find applications as chiral auxiliariesin asymmetric synthesis [98] A solvent-free protocol forthe synthesis of 120573-amino esters and nitriles has been devel-oped via conjugate addition of amines to electron-deficientalkenes promoted on silica gel The silica surface may berecovered and recycled Both aliphatic and aromatic primaryor secondary amines worked efficiently to yield the desiredadducts in good to excellent yields (Scheme 7) [99] Themethod has been found to be mostly successful when thesilica gel of the type used for thin layer chromatography isused Bulky hindered secondary amines such as diisopropy-lamine and dicyclohexylamine that were previously reportedto be unproductive could efficiently undergo aza-Michaeladditions to produce corresponding 120573-amino esters [100]It was interesting to see that o-amino thiol bearing bothheteroatoms (N and S) could afford the bis-adduct whichindicates that thiols are also reactive under similar conditions(Scheme 7)

In general the reactions proceed smoothly under solvent-free conditions except in the eventual purification by columnchromatography Few reactions have been scaled up to10mmol of the amines and the desired products are isolatedwithout any significant change of yield The applicabilityof this ldquogreenrdquo methodology to a diverse variety of aminesincluding aromatic and sterically hindered amines remains tobe the attractive feature and can be utilized by synthetic andindustrial chemists

32 Selective 119873-Alkylation of Amines Further applicationof silica gel has been observed in selective N-alkylation ofamines Traditionally amines are alkylated in solution phaseusing inorganic acids as the catalysts and alkyl halides ordimethyl sulphate as the alkylating agents [101ndash111] besidesmethanol [112] and dimethyl carbonate [113] However yieldsor product-selectivity (mono- or bis-alkylations) are withfew exceptions low and depend on the nature of the catalystsand reaction conditions Though direct nucleophilic attackof amines to alkyl halides using a strong base is the moststraightforward procedure over alkylation use of strong


HO

ON

N

OBr

N

N

O

O

N

N

+ KFalumina

NH2

NH2

R1

R2

R2

R2

R3

R2

R2

R2

R2

R2

R3

R1

R1

R1

R1 = H Me COPhR2 = Ph p-MePh p-MeOPh Furan

R1 = H MeR2 = H Me Et OMe Br Cl I NO2 OH

R1 = H Me COPhR2 = H Me Et Ph p-MePh p-MeOPh FuranR3 = H Me Et n-Pr Ph p-MePh p-MeOPh Furan

Scheme 6

N HSilica gel N

SH

COOEtHN

S

COOEtCOOEt

88Silica gel

R2

R1 R3

R1 = R2 = H alkyl arylR3 = COOEt CN

1ndash12 hR2

R1

R3

(50ndash99)

NH2

40ndash70∘C+

+12h70∘C

Scheme 7

base and other harsh conditions greatly limit providing apractical generalized and selective procedure In contin-uation to explore organic reactions using solid surfaces ahighly selective procedure for mono- and bis-alkylationshas been developed via N-alkylation of amines with alkylhalides in solid phase using silica at room temperature(Scheme 8) [114] The procedure is simple and extremelyuseful for the control of the mono- bis- or overalkylationsby varying the reaction conditions and molar proportionsof amines and alkyl halides The selectivity for mono- orbis-alkylations greatly depends on temperature time of thereaction proportion of the reactants and also partly onthe type of silica gel Inactivated alkyl halides reacted withanilines to produce preferably the monoalkylated anilinesin major quantities even after using excess alkyl halide andcontinuing the reaction for prolonged time The methodwas applied successfully to aliphatic bis-amine such asethylene diamine and reaction with benzyl chloride or allylbromide afforded the desired tetra-alkylated product in 73ndash79 yields Selectivity of mono- and bis-alkylations underdifferent conditions has been further broadened to synthesizeunsymmetrical trialkylaryl amines (Scheme 8) The silicagel after purification and activation can be reused for tenconsecutive runs (tested) without any substantial reductionin the yield as is observed from the recycling experiment

Table 1 Reaction of thiophenol with acetyl chloride on variousinorganic solid supports

Solid supporta Time (min) Acetylationb

Silica 120 92Neutral alumina 120 64Bentonite 30 56Mol Sieves 4 A 120 20Talc 60 39Neat 120 NilaSolid supports used 200mgmmolminus1 byield by HPLC analysis along withanother product (disulfide) and unreacted thiophenol

33 119878-Acylation and Alkylation of Thiols Acylation andalkylation of thiols are essential transformations in organicsynthesis and often used for protection of thiols and arealso known in several biological phenomena [115ndash119] S-Acylation is the posttranslational attachment of fatty acidsto cysteine residues [120] S-Acylated peptides have manypotential uses for elucidating the biophysical structuraland other properties of numerous S-acylated proteins ofmammalian cells [121 122] On the other hand thioethersare useful class of organic compounds and find versatileapplications as key reagents in organic synthesis bioor-ganic heterocyclic and medicinal chemistry The promisingsolvent-free and highly selective N-alkylation promoted bysilica gel has prompted to investigate S-alkylation and S-acylation reactions Initial studies revealed that the reactionbetween thiophenol and acetyl chloride could be achieved atroom temperature when stirred with silica gel under solvent-free conditions producing S-phenyl ethanethioate in 93yield Neither acetic anhydride nor acetic acid was found tobe effective for a similar conversion Silica gel was also foundto be a much better choice for promoting the S-acetylationreaction while neutral alumina yielded the thioester in 64yield and bentonite ormolecular sieves afforded considerableamounts of disulfide (Table 1)


R X(1 Equiv)

R X(22 Equiv)

Silica gelRTSilica gelRTRN

R RN

H

High selectivity on silicaHigh recycling capability

Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2

1ndash26 h3ndash18 h

CH3(CH2)4Br (CH2)4CH3

Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R

Silica gelRT24 examples19 examples

RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2

n = 0ndash3 n = 0ndash3

Scheme 9

Further attempts have been made to obtain general andefficient conditions for the S-acylation and S-alkylation reac-tions of several aromatic and aliphatic thiols with differentacid chlorides and activated alkyl halides respectively in thepresence of silica gel (Scheme 9) A smooth conversion wasobserved in each case affording the desired products in goodto excellent yields Moreover it was found that the recoveredsilica can be reused for seven consecutive runs without anyappreciable loss of activity [123]

34 Selective Synthesis of 12-Disubstituted BenzimidazolesFunctionalized benzimidazoles represent an important classof N-containing heterocyclic compounds and have receivedconsiderable attention in recent times because of their vastapplications as antiulcer antihypertensive antiviral antifun-gal anticancer and antihistamines among others and alsoact as ligands for complexation with transition metals whichare used for modeling biological systems [124ndash127] Severalsynthetic strategies have been developed for the preparationof functionalized benzimidazoles [128ndash140]

Synthetic methods for 12-disubstituted benzimidazoles3 often are associated with cooccurrence of several sidereactions and by-products as shown in Scheme 10

An efficient simple protocol has been developed forhighly selective synthesis of 12-disubstituted benzimidazole3 catalyzed by iron(III) sulfate supported on silica at ambienttemperature under solvent-free conditions (Scheme 11) [141]Silica-supported iron catalysts have been prepared and usedin affecting various organic reactions [142ndash148] Aldehydesbearing different functional groups as well as heteroarylaldehydes reacted smoothly with o-PDs leading to the for-mation of corresponding 12-disubstituted benzimidazoleswith complete selectivity and in good to excellent yields No

electronic or steric impact was found to be prominent in theselective formation of 3

Although the exact mechanism is not clear the Lewisacid-mediated mechanism is expected to play (Figure 2)Adsorption of iron(III) sulfate on the surface of silica isbelieved to make polynuclear iron(III) hydroxyl complexes 4[149] Silica being awater absorbent could facilitate formationof the bis-Schiff base 5 which has been reported and indeedwas isolated when the reaction was stopped after 20minThe Schiff base 5 may undergo cyclization followed by 13-hydride shift induced by electrophilic catalyst [150] resultingin the formation of the 12-disubstituted benzimidazole 3An indirect evidence in favour of 13-hydride shift of theSchiff base 5 isolated from o-phenylenediamine and salicy-laldehyde (6) showed reluctance to undergo cyclization atroom temperatureThis is possibly because of intramolecularHndashbonding with ondashOH group [151] making the nitrogenless nucleophilic and thus required higher temperature forthe cyclization (Scheme 12) The existence of intramolecularhydrogen bonding in the Schiff base (6) was also demon-strated by 1HndashNMR studies at varying concentrations of theSchiff base (6) [141]

4 Reactions on Organic Polymer Support

The polymeric supports used by Merrifield for his earlywork in solid-phase peptide synthesis were based on 2divinylbenzene (DVB) cross-linked polystyrenes (PS) PShas been found to be one of the most accepted polymericmaterial used in various synthesis because it is inexpensivereadily available mechanically robust chemically inert andsmoothly functionalizable [152 153] Crosslinking impartsmechanical stability improved diffusion and swelling proper-ties to the resin Various percentages and types of crosslinkingagents have been incorporated into the PS resins the mostcommon being DVB but other examples include ethyleneglycol dimethylacrylate (EGDMA) and tetraethylene glycoldiacrylate (TEGDA) to give different solvation properties[154 155] A schematic representation of polymerization ofstyrene with functionalized monomers is shown in Figure 3

TentaGel [156] and ArgoGel [157] (Figure 4) are twocommercially available examples where the incorporationof the PEG chains dramatically increases resin compatibilitywith polar solvents


CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N

NIron(III)sulfate silica gel

Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO

Iron(III)sulfate-silica

N

No-OH

o -OH

Iron(III)sulfate-silica Iron(III)sulfate-silica

(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12

Generally reagents and catalysts are immobilized ontopolymer surface involving (i) covalent binding (ii) entrap-ment where a preformed catalyst is enveloped within apolymer network and (iii) ion-pairing where cations oranions are bound to complementary resin sites [158] Immo-bilization of reagents and catalysts can also be done bymicroencapsulation [159] where the polymers are physicallyenveloped by thin films of reagents or catalysts and perhapsstabilized by the interaction between 120587 electrons of benzenerings of the polystyrene used as a polymer backbone andvacant orbital of reagents or catalysts [160]

41 Catalytic Transfer Hydrogenation (CTH) Using SupportedFormate Catalytic transfer hydrogenation (CTH) with theaid of a stable hydrogen donor is a useful alternativemethod to catalytic hydrogenation usingmolecular hydrogen(H2) [161ndash166] In transfer hydrogenation several organic

molecules such as hydrocarbons primary and secondaryalcohols and formic acid and its salts have been employedas the hydrogen source [167ndash173] The use of reagents such ashydrazine is less frequent The use of a hydrogen donor hassome advantages over the use of molecular hydrogen since itavoids the risks and the constraints associated with hydrogengas as well as the necessity for using pressure vessels and otherequipment

411 Palladium-Catalyzed Transfer Hydrogenation (CTH)of Alkenes and Imines In connection with our interestin palladium-catalyzed transfer hydrogenation (CTH) ofalkenes and imines using potassium formate [82] we wantedto develop a stable hydrogen donor anchored to a solidsurface to be used in CTH (Figure 5) In search of suitablepolymeric supports ion-exchange resins were used It wasobserved that Amberlite IRA-420 anion (chloride form)exchange resins commercially available and inexpensivepolyionic resin could exchange the anion with formate anion(HCOOminus) easily and quantitatively The resulting AmberliteResin Formate (anion) designated as ARF could be utilizedas a solid-phase version of theH-donor in Pd-catalyzed CTHThe ARF was air stable can be stored for several weeks andalso can be recovered from a reaction and reused Severalalkenes and iminewere thus hydrogenated using theARF andcatalytic amount of palladium acetate under mild conditions(Scheme 13) [174]

The reduction of the CndashC double bond proceededsmoothly at 70ndash75∘C requiring only gentle agitation work-up was then achieved by simple filtration extraction withdiethyl ether and followed by evaporation of the solvent Boththe cyano and ester groups remained unaffected under thereaction conditions The reduction of a dicyanoalkylidenederivative was found to occur with similar efficiency Themethod is operationally simple and applicable to a varietyof unsaturated organic compounds The use of a palladiumcatalyst exhibits some substrate selectivity and the transfer


O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer

Divinylbenzenecrosslinking element

Functionalizedmonomer

Radicalinitiator

2

Polystyrenechain

Crosslink

Functionalized aryl group for attachmentof linkers and substrates

Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4

hydrogenation appears to proceed at a slower rate in compar-ison to that of potassium formate

412 Palladium-Catalyzed Transfer Hydrogenation (CTH) ofNitroarenes With the success of reducing CndashC and CndashNbonds using the solid-supported formate as suitable H-donor[174] further attempts have been made in the reduction ofnitroarenes to anilines which is a synthetically importanttransformation both in the laboratory and in industry Formicacids and their salts are frequently employed as H-donor inCTH reactions and nitroarenes can be reduced to anilinesusing ammonium formate and Pd-C or Raney nickel [175ndash177] However reductive elimination of halogen substituentson the aromatic nucleus and formation of N-formyl deriva-tives instead of arylamines are the major drawbacks of usingammonium formatePd-C On the other hand combinationof NaBH

4with Cu(II) Co(II) or Rh(III) halides has been

used for reduction of the nitro group which is inert toNaBH4

itself [178 179] Metal hydrides are however water-sensitiveas well as expensive chemicals The reduction of nitro groupwas carried out using 2mol Pd(OAc)

2and (aminomethyl)

polystyrene with formate anion (ARF) in a minimum quan-tity of DMF at 100ndash120∘C for 6ndash14 h (Scheme 14) [180]

413 Ruthenium-Catalyzed Transfer Hydrogenation (CTH)of Carbonyl Groups Reduction of carbonyl functionalityby transition metal-catalyzed transfer hydrogenation (CTH)with the aid of a suitable H-donor is a valuable synthetictool Generally reduction of aryl ketones is performedunder CTH using isopropyl alcohol as the H-donor [181ndash186] In order to check the efficiency of Amberlite ResinFormate (ARF) reduction of aryl ketones was studied usingthe combination of catalytic amount of Ru(III) salts and

the polyionic resin formateThe results constitute an efficientmethod for chemoselective transfer hydrogenation of arylaldehydes with the aid of resin-supported formate in thepresence of catalytic (25mol) amount of commerciallyavailable RuCl

3sdot3H2O in DMF or DMA solution as outlined

in Scheme 15 [187]On the basis of comparison with a well-defined Ru(II)

complex [Dichloro(p-cymene)ruthenium(II)] dimer (2mol) under similar conditions it is presumed that the Ru(III)salt might undergo in situ reduction to Ru(II) whichthen catalyzes the hydrogenation of the aldehydes Aryland heteroaryl aldehydes substituted with various electronwithdrawing and donating groups and the presence of o-substituents do not seem to influence the rate of thereduction as revealed by the similarity of the results andall compounds afford corresponding alcohols in high yieldsSeveral other potential reducible groups like halogens nitroand so forth are not affected under the reaction conditionsAliphatic aldehydes are also reduced to corresponding alco-hols efficiently Interestingly aryl ketones are not reducedunder similar conditions The selectivity between aryl alde-hyde and aryl ketone might offer a distinct advantage whenboth the functional groups are present Thus an experimentwas conducted taking a mixture of an aryl aldehyde and anaryl ketone (1mmol each) at 85∘C to finally afford the reducedalcohol from the aryl aldehyde but the aryl ketone remainedunchanged and recovered almost quantitativelyWhereas arylketones are not reduced under the conditions reduction ofbenzil to benzoin proceeds smoothly in good to excellentyields Distinct advantages of cleaner reaction and easyisolation of the product are notable features when comparingthe application of heterogeneous ARF and a simple formatesalt (herein potassium formate) in homogeneous phase


HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)

Amberlite IRA-420 Chloride form taken in water

Amberlite IRA-420 Formate form

NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4

R1 = R2 = Ph Ar HR3 = R4 = CN COOEt COOMe NHBoc H PhX = C N

Scheme 13

HCOONO2

R1

NR3

Pd(OAc)2DMF100ndash120∘C

NH2

R1

Scheme 14

The reaction conditions appear to be mild and base-free andgive high yields of the corresponding alcohols and free of anyby-product

414 Catalytic Transfer Hydrogenation (CTH) Using Coim-mobilized CatalystReagent It is well established that Pdpromotes direct oxidation of formic acid to carbon dioxide

[173] The combination of formic acid and palladium acetateis known to undergo anionic ligand exchange to form apalladium diformate complex eventually producing Pd(0)through decarboxylation and loss of molecular hydrogenThe high degree of chemoselectivity in palladium-catalyzedtransfer hydrogenation using HCOOH or its salts has beenexplained on the basis that the hydrogen is delivered directlyfrom a palladium formate species which has much strongerhydridic nature as compared to that of a palladium hydridespecies (Scheme 16)

In CTH either a source of palladium is required for eachoperation or it may be supported by a polymer frameworkand reused several times It is reasoned that the palladiumcatalyst might be anchored to the ARF so that it could be usedand recycled (Scheme 17) It is observed that palladium canbe immobilized onto the polyionic resins surface and usedefficiently in the CTH of a variety of functional groupsThusa new solid-phase entity (ARF-Pd) has been developed coim-mobilizing both the catalyst and the reagent and expected tobe potentially useful in CTH of different functional groups

The efficiency and stability of this newly developed ARF-Pd was first examined in the reduction of electron-deficientalkenes conjugated with ketones nitriles and carboxylateesters (Scheme 18) [188] Further applications of this new het-erogeneous reductive system are tested with 12-dicarbonylcompounds When benzil or substituted benzil is used as thesubstrate the reduction of one of the carbonyl groups withARF-Pd in DMF at 110∘C has been completed within 10ndash12 h to furnish the corresponding120572-hydroxyketone (benzoin)in a 77ndash88 yield Aromatic nitro compounds are alsoreduced using the coimmobilized palladium in DMF Thisnew technique is highly chemoselective in the reduction


OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3

RuCl3 ∙ 3H2O (25 mol)DMF 90∘C 12 h

RuCl3 ∙ 3H2O (25 mol)

(70ndash96)

R1 = H COArR2 = H Alkyl Br Cl F NO2 OMe OAr

ARF (05 g mmolminus1)

+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17

of alkenes imines and nitro groups thus establishing anefficient environmentally benign economically friendly andsustainable process

42 CndashC Cross-Coupling Reactions Transition metal-cata-lyzed cross-coupling reactions constitute the central part ofcontemporary organic synthesis [189ndash192] In particular thepalladium-catalyzed carbon-carbon bond-forming processesrepresent the foremost in the arena of organic process devel-opment The Heck Suzuki-Miyaura Sonogashira reactions(Scheme 19) are excellent tools for carbon-carbon couplingreactions between aryl halides or triflates and suitable part-ners [193]

The coupling of terminal alkynes with an aryl or vinylhalide performed with a palladium catalyst a copper co-catalyst and an amine base is termed as the Sonogashiracoupling reaction [194ndash206] Typically the reaction requiresanhydrous and anaerobic conditions but the newer proce-dures which have been developed show that the restrictionsare not so important

Over the last decade commendable research has beendone to achieve significant developments and to estab-lish practical methodologies [207ndash210] Widespread uses ofpalladium-catalyzed coupling reactions are found in modernorganic synthesis because the resulting coupled products

often find good applications in the preparation of materialspharmaceuticals and other bioactive compounds [211ndash218]As a part of recognition of these extremely useful reactionsNobel prize was awarded to Heck Suzuki and Negishi[219] Many efforts have been reported to immobilize Pdusing a support encapsulating in a polymer or dendrimeror immobilization by ligandpolymer but the problem ofleaching and recyclability still exists [220ndash236]

421 Use of ARF-Pd in CndashC Cross-Coupling Reactions Excel-lent activity high selectivity and reusability of the ARF-Pdas potential reductive system have prompted to explore it asa viable heterogeneous Pd catalyst in various CndashC couplingreactions (Scheme 20) [237] One of the key questions onwhich the researchers have focused is ldquohow canminimizationof catalyst cost and catalyst contamination of the product bebest achievedrdquo It may be noted that the investigation of theheterogeneous ARF-Pd has addressed a great extent to thisquestion

The catalytic activity of ARF-Pdwas first examined inthe Heck coupling reactions and then for the Suzuki andSonogashira reactions as outlined in Scheme 20

Indeed the Heck coupling between 3-chloroiodobenzeneand ethyl cinnamate in the presence of the heterogeneous cat-alyst ARF-Pd the cross-coupled product trans-ethyl-3-chlo-rocinnamate has been isolated in 86 yield Exclusive trans-selectivity is achieved as is assigned on the basis of the cou-pling constant (119869 = 159Hz) Although several iodoarenesundergo Heck coupling with an alkene interestingly thebromoarenes remain unchanged which is typically seen forother halogens like chloro or fluoro groups attached withthe aromatic moiety The ortho-substituent did not cause anysteric inhibition as usually experienced in other couplingreaction which may be attributed to high activity of thecatalyst

The Suzuki-Miyaura reaction (Scheme 20) has beencarried out using 4-bromo-2-methyl anisole phenyl boronicacidNa

2CO3in the presence ofARF-PdHeating themixture

at 110∘C for 5 h under N2followed by removal of ARF-

Pd by simple filtration and chromatographic purification of


ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1

R1 R2 = H Ph ArR3 R4 = CN COOEt COAr NHBocX = C N

50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19

the residual mixture furnished the desired unsymmetricalbiphenyl in 82 yield Both bis- and tris-coupled aryl ben-zenes have also been prepared in good to excellent yieldswhen reactions are performed using di- and tribromoarenesrespectively showing notable activity of the heterogeneouspalladium catalysts (ARF-Pd) It may be noted that ortho-dibromobenzene affords a mixture of mono- and biscoupledproducts in the presence of Pd(OAc)

2as the source of

palladiumThe Sonogashira coupling reaction normally requires 1ndash

10mol Pd(PPh3)2Cl2(or Pd(PPh

3)4) and copper(I) iodide

as the catalytic system Using the ARF-Pd the reaction of3-iodoanisole and 1-ethynyl-4-methylbenzene carried out inthe presence of Et

3Nas the base in acetonitrile solvent at 80∘C

for 6 h afforded the desired cross-coupled product in excellentyield (Scheme 20) Similar coupling reactions with otheriodoarenes and acetylenes are also found to be successful[237]

In all cases products are isolated in pure form simplyby filtering off the resin-bound palladium catalyst followedby chromatographic purification of the concentrated residueRecycling experiments are tested by taking Suzuki-Miyauracoupling between 14-dibromobenzene and phenylboronicacid The results have revealed that the catalyst is remarkably

active even in the fifth run Consecutive five runs were testedto evaluate the activity of ARF-Pd The palladium contentthroughout the recycling runs remained at a steady state withmarginal increase of Pd distribution on the resin surfacewhich might be due to repeated agitation of the beads duringthe reactions and exposing more surface area with palladiumcontent

422 Suzuki Coupling Using Solid-Phase ImmobilizedOrganoboron Species The concept of a resin-capture-releasetechnique generating the polymer-bound reactive specieshas been established as a potential method for severalorganic transformations [238ndash240] A variety of techniquesare reported in the literature to immobilize differentcomponents of Suzuki cross-coupling reaction [241ndash253]Polymer-bound boronic acids though reported as early as1976 [254] Frenette and Friesen [255] investigated theirutility in Suzuki coupling reaction in 1994

Further application of polyionic resin bound reagentsandor catalysts has been established when an ion-exchangeresin-supported organoborate species is derived as aheterogeneous phenylating agent [256] Thus Amberliteion-exchange resins (chloride form) are exchanged withtetraphenylborate anion (Ph

4Bminus) by continuous rinsing with

an aqueous solution of NaBPh4until the washings gave

negative response to chloride anion (monitored with AgNO3

solution followed by addition of aqueous ammonia) Thepolyionic resins with the tetraphenylborate counter anion(Ph4Bminus) have been used directly for the Suzuki coupling

reaction Initial studies on coupling with 3-iodotoluene inthe presence of palladium catalyst [Pd(OAc)

2 2mol and

Na2CO3 1 equiv] afford the unsymmetrical biphenyl in

90 yield (Scheme 21 condition (a)) Similar coupling of 3-iodotoluene and NaBPh

4in the presence of Na

2CO3afforded

only 43 yield of the coupled product (Scheme 21 condition(b)) However on increasing the quantity of NaBPh

4 the

resulting coupled product could be isolated in 88 yield


O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd

90ndash100∘C5 to 10 h

R = Cl F Br OCH3 NH2

OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br

DMF110∘C25 to 6 hN2

Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+

(a) IIINa2CO3 = 11gmmol1 9(b) IIIINa2CO3 = 111 43(c) IIIINa2CO3 = 1251 88(d) IIII = 125 88(e) III = 11gmmol 96

Scheme 21

(Scheme 21 condition (c)) An interesting observation isthat the yield of the coupled product is not influenced by theabsence of base (Scheme 21 conditions (d) and (e)) Suchbase-free conditions for SM reactions could offer significantpractical advantages and have not previously been reportedwith the organoborate ion bound with solid-phase polymericframeworks

423 Organic Disulfide (SndashS Linkage) Synthesis Organicdisulfides (bearing SndashS linkage) are useful compounds ofwidespread occurrence possessing unique and diverse chem-istry in the synthetic biochemical and agrochemical areas[257ndash259] Disulfide-linked aggregates ubiquitously occurin proteins and many other bioactive molecules Disulfidebonds play an important role in the folding and stabilityof some proteins [260 261] Industrially disulfides find vastapplications as vulcanizing agents for rubbers and elastomerscontributing them considerable tensile strength [262 263]Apart from various solution-phase approaches for the syn-thesis of disulfide from thiols and other precursors thereare few reports on the synthesis of disulfides promoted bypolymeric resin hydroxides In a recent report Sengupta andBasu have shown that Amberlyst A-26(OH) can efficientlypromote smooth conversion of disulfides from alkyl and acyl

methyl thiocyanates in good to excellent yields (Scheme 22)They have also demonstrated that the use of polyionic resinhydroxide has resulted in much better results over otherhomogeneous bases like NaOH NH

3 K2CO3[264]

5 Conclusion

Thus a series of reactions has been developed exhibitingthe potential of using both inorganic and organic polymericframeworks as the solid phaseThe present review has shownthat alumina silica surface alone or having doped with vari-ous inorganic salts could be utilized in carrying out differentorganic reactions under solvent-free conditions producingmolecules of biological and industrial importance Similarlypolyionic resins have been shown to immobilize reagentsandor catalysts and employ in transfer hydrogenation ofalkenes imines and nitroarenes and in different CndashC cross-coupling reaction Mild reaction conditions easy work-upprocedure selective synthesis of the target molecules andrecycling capability of the supported reagent or catalyst aresome of the advantages of adopting solid-phase organicreactions Further development of newer solid phases immo-bilization procedures resulting in regular dispersion andfinally their new applications are expected in the years tocome


R SCNor

Ar

OSCN

Amberlyst A-26 (OH) RS R

or

Ar

OS

2

Metal-free on-water procedure

and superior to using other homogeneous bases

S(74ndash92)Water60ndash80∘C

Scheme 22

Acknowledgments

The author Basudeb Basu wishes to thank all the contributorsfrom this research group whose names are in their respectivepublications mentioned in the reference section Financialsupport from the Department of Science and TechnologyIndia is gratefully acknowledged including the ongoingGrant no SRS1OC-862010

References

[1] R B Merrifield ldquoSolid phase peptide synthesis I The synthesisof a tetrapeptiderdquo Journal of the American Chemical Society vol85 no 14 pp 2149ndash2154 1963

[2] G H Posner ldquoOrganicreactions at alumina surfacesrdquo Ange-wandte ChemiemdashInternational Edition vol 17 no 7 pp 487ndash496 1978

[3] A McKillop and K W Young ldquoOrganic synthesis using sup-ported reagentsmdashpart I amp part IIrdquo Synthesis pp 401ndash422 481ndash500 1979

[4] A Cornelis and P Laszlo ldquoClay-supported copper(II) andiron(III) nitrates novel multi-purpose reagents for organicsynthesisrdquo Synthesis no 10 pp 909ndash918 1985

[5] P Laszlo Preparative Chemistry Using Supported ReagentsAcademic Press San Diego Calif USA 1987

[6] E K Smith Solid Supports and Catalyst in Organic SynthesisEllis Horwood Chichester UK 1992

[7] M Balogh and P Laszlo Organic Chemistry Using ClaysSpringer Berlin Germany 1993

[8] J H Clark Catalysis of Organic Reactions by Supported Inor-ganic Reagents VCH New York NY USA 1994

[9] R L Letsinger and V Mahadevan ldquoOligonucleotide synthesison a polymer supportrdquo Journal of the American ChemicalSociety vol 87 no 15 pp 3526ndash3527 1965

[10] J M Fraile J A Mayoral A J Royo et al ldquoSupported chiralamino alcohols and diols functionalized with aluminium andtitanium as catalysts of Diels-Alder reactionrdquo Tetrahedron vol52 no 29 pp 9853ndash9862 1996

[11] A P T Anastas and J C Warner Green Chemistry Theoryand Practice Oxford Science Publications New York NY USA1998

[12] P T Anastas and T Williamson Green Chemistry Frontiersin Benign Chemical Synthesis and Procedures Oxford SciencePublications New York NY USA 1998

[13] J H Clark ldquoGreen chemistry challenges and opportunitiesrdquoGreen Chemistry vol 1 no 1 pp 1ndash8 1999

[14] M Lancaster Green Chemistry An Introductory Text RoyalSociety of Chemistry Cambridge Mass USA 2002

[15] G W V Cave C L Raston and J L Scott ldquoRecent advancesin solventless organic reactions towards benign synthesis with

remarkable versatilityrdquo Chemical Communications no 21 pp2159ndash2169 2001

[16] PHodge andDC SherringtonPolymer-Supported Reactions inOrganic Synthesis John Wiley and Sons Chichester UK 1980

[17] PHodge andDC Sherrington Syntheses and SeparationsUsingFunctional Polymers John Wiley and Sons Chichester UK1988

[18] A Akelah and D C Sherrington ldquoRecent developments in theapplication of functionalized polymers in organic synthesisrdquoPolymer vol 24 no 11 pp 1369ndash1386 1983

[19] J A Gladysz ldquoIntroduction recoverable catalysts and rea-gentsmdashperspective and prospectiverdquo Chemical Reviews vol102 no 10 pp 3215ndash3216 2002

[20] D C Sherrington ldquoPolymer-supported reagents catalysts andsorbents evolution and exploitationmdasha personalized viewrdquoJournal of Polymer Science Part A vol 39 no 14 pp 2364ndash23772001

[21] D C Sherrington ldquoPreparation structure and morphology ofpolymer supportsrdquoChemical Communications no 21 pp 2275ndash2286 1998

[22] P Wentworth and K D Janda ldquoLiquid-phase chemistry recentadvances in soluble polymer-supported catalysts reagents andsynthesisrdquo Chemical Communications no 19 pp 1917ndash19241999

[23] J S Yadav and H M Meshram ldquoGreen twist to an old themeAn eco-friendly approachrdquo Pure and Applied Chemistry vol 73no 1 pp 199ndash203 2001

[24] M Lebl ldquoSolid-phase synthesis on planar supportsrdquo Biopoly-mers vol 47 pp 397ndash404 1998

[25] N J Maeji R M Valerio A M Bray R A Campbell and HMGeysen ldquoGrafted supports usedwith themultipinmethod ofpeptide synthesisrdquo Reactive Polymers vol 22 no 3 pp 203ndash2121994

[26] N Hird I Hughes D Hunter M G J T Morrison D CSherrington and L Stevenson ldquoPolymer discsmdashan alternativesupport format for solid phase synthesisrdquo Tetrahedron vol 55no 31 pp 9575ndash9584 1999

[27] R C D Brown ldquoRecent developments in solid-phase organicsynthesisrdquo Journal of the Chemical Society Perkin Transactions1 no 19 pp 3293ndash3320 1998

[28] D C Sherrington ldquoPolymer-supported synthesisrdquo inChemistryof Waste Minimisation J H Clark Ed chapter 6 BlackieAcademic London UK 1995

[29] J H Clark A P Kybett and D J Macquarrie SupportedReagents Preparation Analysis and Applications VCH NewYork NY USA 1992

[30] D J Gravert and K D Janda ldquoOrganic synthesis on solu-ble polymer supports liquid-phase methodologiesrdquo ChemicalReviews vol 97 no 2 pp 489ndash509 1997

[31] J O Metzger ldquoSolvent-free organic synthesesrdquo AngewandteChemiemdashInternational Edition vol 37 no 21 pp 2975ndash29781998

[32] M S Singh and S Chowdhury ldquoRecent developments insolvent-free multicomponent reactions a perfect synergy foreco-compatible organic synthesisrdquo RSC Advances vol 2 no 11pp 4547ndash4592 2012

[33] K Tanaka Solvent-Free Organic Synthesis Wiley-VCH GmbHamp Co KGaA Weinheim Germany 2003

[34] R S Varma ldquoSolvent-free organic syntheses using supportedreagents and microwave irradiationrdquo Green Chemistry vol 1no 1 pp 43ndash55 1999


[35] R S Varma ldquoSolvent-free accelerated organic syntheses usingmicrowavesrdquo Pure and Applied Chemistry vol 73 no 1 pp 193ndash198 2001

[36] M H Sarvari and H Sharghi ldquoZinc oxide (ZnO) as a newhighly efficient and reusable catalyst for acylation of alcoholsphenols and amines under solvent free conditionsrdquo Tetrahe-dron vol 61 no 46 pp 10903ndash10907 2005

[37] K Wilson and J H Clark ldquoSolid acids and their use asenvironmentally friendly catalysts in organic synthesisrdquo Pureand Applied Chemistry vol 72 no 7 pp 1313ndash1319 2000

[38] A Loupy ldquoSolvent-free reactionsrdquo Topics in Current Chemistryvol 206 pp 153ndash207 1999

[39] R H Andreatta and H Rink ldquoZur problematik der peptidsyn-these an tragern beitrag eines neuen Verfahrens mit loslichentragernrdquo Helvetica Chimica Acta vol 56 no 4 pp 1205ndash12181973

[40] M M Shemyakin Y A Ovchinnikov A A Kinyushkin andI V Kozhevnikova ldquoSynthesis of peptides in solution on apolymeric support I Synthesis of glycylglycyl-l-leucylglycinerdquoTetrahedron Letters vol 6 no 27 pp 2323ndash2327 1965

[41] S H L Chiu and L Anderson ldquoOligosaccharide synthesis bythe thioglycoside scheme on soluble and insoluble polystyrenesupportsrdquo Carbohydrate Research vol 50 no 2 pp 227ndash2381976

[42] S Chert and K D Janda ldquoSynthesis of prostaglandin E2 methylester on a soluble-polymer support for the construction ofprostanoid librariesrdquo Journal of the American Chemical Societyvol 119 no 37 pp 8724ndash8725 1997

[43] H Hayatsu and H G Khorana ldquoStudies on polynucleotidesLXXII Deoxyribooligonucleotide synthesis on a polymer sup-portrdquo Journal of the American Chemical Society vol 89 no 15pp 3880ndash3887 1967

[44] M Narita ldquoLiquid phase peptide synthesis by the fragmentcondensation on soluble polymer support I Efficient couplingand relative reactivity of a peptide fragment with variouscoupling reagentsrdquo Bulletin of the Chemical Society of Japan vol51 no 5 pp 1477ndash1480 1978

[45] E Cramer R Helbig H Hettler K H Scheit and H SeligerldquoOligonucleotid-Synthese an einem loslichen Polymeren alsTragerrdquo Angewandte Chemie vol 78 no 12 pp 640ndash641 1966

[46] R L Letsinger andM J Kornet ldquoPopcorn polymer as a supportin multistep synthesesrdquo Journal of the American ChemicalSociety vol 85 no 19 pp 3045ndash3046 1963

[47] A Guyot ldquoPolymer supports with high accessibilityrdquo Pure andApplied Chemistry vol 60 no 3 pp 365ndash376 1988

[48] F Svec and J M J Frchet ldquoNew designs of macroporous poly-mers and supports from separation to biocatalysisrdquo Science vol273 no 5272 pp 205ndash211 1996

[49] M Hori D J Gravert R Wentworth and K D JandaldquoInvestigating highly crosslinked macroporous resins for solid-phase synthesisrdquo Bioorganic ampMedicinal Chemistry Letters vol8 no 17 pp 2363ndash2368 1998

[50] E R L Malenfant and J M J Frchet ldquoThe first solid-phasesynthesis of oligothiophenesrdquo Chemical Communications no23 pp 2657ndash2658 1998

[51] GW Kabalka and RM Pagni ldquoOrganic reactions on aluminardquoTetrahedron vol 53 no 24 pp 7999ndash8065 1997

[52] B Basu and BMandal ldquoKFalumina a potential heterogeneousbase for organic reactionsrdquo Current Organic Chemistry vol 15no 22 pp 3870ndash3893 2011

[53] T Ando S J Brown J H Clark et al ldquoAlumina-supportedfluoride reagents for organic synthesis optimisation of reagentpreparation and elucidation of the active speciesrdquo Journal ofthe Chemical Society Perkin Transactions 2 no 8 pp 1133ndash11391986

[54] T Ando J H Clark D G Cork and T Kimura ldquoSurfaceanalysis of MF-aluminas and related supported reagents byscanning electron microscopyrdquo Bulletin of the Chemical Societyof Japan vol 59 no 10 pp 3281ndash3282 1986

[55] T Ando J H Clark D G Cork T Hanafusa J Ichihara and TKimura ldquoFluoride-alumina reagents the active basic speciesrdquoTetrahedron Letters vol 28 no 13 pp 1421ndash1424 1987

[56] J H Clark ldquoFluoride ion as a base in organic synthesisrdquoChemical Reviews vol 80 no 5 pp 429ndash452 1980

[57] A LoupyA Petit JHamelin F Texier-Boullet P Jacquault andD Mathe ldquoNew solvent-free organic synthesis using focusedmicrowavesrdquo Synthesis no 9 pp 1213ndash1234 1998

[58] A Guram and S L Buchwald ldquoPalladium-catalyzed aromaticaminations with in situ generated aminostannanesrdquo Journal ofthe American Chemical Society vol 116 no 17 pp 7901ndash79021994

[59] J P Wolfe S Wagaw J-F Marcoux and S L Buchwald ldquoRatio-nal development of practical catalysts for aromatic carbon-nitrogen bond formationrdquo Accounts of Chemical Research vol31 no 12 pp 805ndash818 1998

[60] J Louie and J F Hartwig ldquoPalladium-catalyzed synthesisof arylamines from aryl halides Mechanistic studies lead tocoupling in the absence of tin reagentsrdquoTetrahedron Letters vol36 no 21 pp 3609ndash3612 1995

[61] J F Hartwig ldquoApproaches to catalyst discovery New carbon-heteroatom and carbon-carbon bond formationrdquo Pure andApplied Chemistry vol 71 no 8 pp 1417ndash1423 1999

[62] D W Old J P Wolfe and S L Buchwald ldquoA highly active cat-alyst for palladium-catalyzed cross-coupling reactions room-temperature Suzuki couplings and amination of unactivatedaryl chloridesrdquo Journal of the American Chemical Society vol120 no 37 pp 9722ndash9723 1998

[63] B Basu S Jha N K Mridha and M M H BhuiyanldquoPalladium-catalysed amination of halopyridines on a KF-alumina surfacerdquo Tetrahedron Letters vol 43 no 44 pp 7967ndash7969 2002

[64] B Basu P Das A K Nanda S Das and S Sarkar ldquoPalladium-catalyzed selective amination of haloaromatics on KF-aluminasurfacerdquo Synlett no 8 pp 1275ndash1278 2005

[65] D A Oare and C H Heathcock ldquoStereochemistry of the base-promoted Michael addition reactionrdquo in Topics in Stereochem-istry E L Eliel and S HWillen Eds vol 19 p 277 JohnWileyand Sons New York NY USA 1989

[66] J DrsquoAngelo G Revial P R R Costa R N Castro and O AC Antunes ldquoAsymmetric Michael addition of chiral imines tophenylvinylsulfone preparation of key chiral building blocksfor the synthesis of Aspidosperma and Hunteria alkaloidsrdquoTetrahedron Asymmetry vol 2 no 3 pp 199ndash202 1991

[67] B List P Pojarliev andH JMartin ldquoEfficient proline-catalyzedMichael additions of unmodified ketones to nitro olefinsrdquoOrganic Letters vol 3 no 16 pp 2423ndash2425 2001

[68] A Alexakis and O Andrey ldquoDiamine-catalyzed asymmetricMichael additions of aldehydes and ketones to nitrostyrenerdquoOrganic Letters vol 4 no 21 pp 3611ndash3614 2002

[69] B Basu P Das and I Hossain ldquoKF-alumina-mediated selectivedouble Michael additions of aryl methyl ketones a facile


entry to the synthesis of functionalized pimelate esters andderivativesrdquo Synlett no 12 pp 2224ndash2226 2004

[70] D A Horton G T Bourne and M L Smythe ldquoThe combi-natorial synthesis of bicyclic privileged structures or privilegedsubstructuresrdquo Chemical Reviews vol 103 no 3 pp 893ndash9302003

[71] G Bringmann C Gunther M Ochse O Schupp and S TaslerldquoBiaryls in nature a multi-facetted class of stereochemicallybiosynthetically and pharmacologically intriguing secondarymetabolitesrdquo in Progress in the Chemistry of Organic NaturalProducts W Herz H Falk G W Kirby and R E Moore Edsvol 82 Springer New York NY USA 2001

[72] P J Hajduk M Bures J Praestgaard and S W Fesik ldquoPrivi-legedmolecules for protein binding identified fromNMR-basedscreeningrdquo Journal of Medicinal Chemistry vol 43 no 18 pp3443ndash3447 2000

[73] G W Bemis and M A Murcko ldquoThe properties of knowndrugs 1 Molecular frameworksrdquo Journal of Medicinal Chem-istry vol 39 no 15 pp 2887ndash2893 1996

[74] U Schmidt V Leitenberger H Griesser J Schmidt and RMeyer ldquoTotal synthesis of the biphenomycins V Synthesis ofbiphenomycin Ardquo Synthesis no 12 pp 1248ndash1254 1992

[75] U Schmidt R Meyer V Leitenberger H Griesser and ALieberknecht ldquoTotal synthesis of the biphenomycins III Syn-thesis of biphenomycin Brdquo Synthesis no 10 pp 1025ndash1030 1992

[76] A Markham and K L Goa ldquoValsartanrdquo Drugs vol 54 no 2pp 299ndash311 1997

[77] K F Croom and G M Keating ldquoValsartanrdquo American Journalof Cardiovascular Drugs vol 4 no 6 pp 395ndash404 2004

[78] M Sharpe B Jarvis and K L Goa ldquoTelmisartan a review of itsuse in hypertensionrdquo Drugs vol 61 no 10 pp 1501ndash1529 2001

[79] S Yusuf ldquoFrom the hope to the ontarget and the transcendstudies challenges in improving prognosisrdquo American Journalof Cardiology vol 89 no 2 pp 18ndash25 2002

[80] M E Matheron and M Porchas ldquoActivity of boscalid fen-hexamid fluazinam fludioxonil and vinclozolin on growthof sclerotinia minor and s sclerotiorum and development oflettuce droprdquo Plant Disease vol 88 no 6 pp 665ndash668 2004

[81] B Basu P Das M M H Bhuiyan and S Jha ldquoMicrowave-assisted Suzuki coupling on a KF-alumina surface synthesis ofpolyarylsrdquo Tetrahedron Letters vol 44 no 19 pp 3817ndash38202003

[82] P Das and B Basu ldquoMicrowave-assisted copper promoted N-arylation of amines with aryl boronic acidssalts on a KF-alumina surfacerdquo Synthetic Communications vol 34 no 12 pp2177ndash2184 2004

[83] A Gomtsyan E K Bayburt R G Schmidt et al ldquoNovel tran-sient receptor potential vanilloid 1 receptor antagonists for thetreatment of pain Structure-activity relationships for ureaswithquinoline isoquinoline quinazoline phthalazine quinoxaliueand cinnolinemoietiesrdquo Journal ofMedicinal Chemistry vol 48no 3 pp 744ndash752 2005

[84] R Sarges H R Howard R G Browne L A Lebel PA Seymour and B K Koe ldquo4-amino[124]triazolo[43-a]quinoxalines A novel class of potent adenosine receptorantagonists and potential rapid-onset antidepressantsrdquo Journalof Medicinal Chemistry vol 33 no 8 pp 2240ndash2254 1990

[85] L E Seitz W J Suling and R C Reynolds ldquoSynthesisand antimycobacterial activity of pyrazine and quinoxalinederivativesrdquo Journal of Medicinal Chemistry vol 45 no 25 pp5604ndash5606 2002

[86] A Jaso B Zarranz I Aldana and A Monge ldquoSynthesisof new quinoxaline-2-carboxylate 14-dioxide derivatives asanti-mycobacterium tuberculosis agentsrdquo Journal of MedicinalChemistry vol 48 no 6 pp 2019ndash2025 2005

[87] WHeM RMyers B Hanney et al ldquoPotent quinoxaline-basedinhibitors of PDGF receptor tyrosine kinase activitymdashpart 2the synthesis and biological activities of RPR127963 an orallybioavailable inhibitorrdquo Bioorganic and Medicinal ChemistryLetters vol 13 no 18 pp 3097ndash3100 2003

[88] M M Ali M M F Ismail M S A El-Gaby M A Zahran andY A Ammar ldquoSynthesis and antimicrobial activities of somenovel quinoxalinone derivativesrdquo Molecules vol 5 no 6 pp864ndash873 2000

[89] G Saka K Makino and Y Kurasawa ldquoRecent progress inthe quinoxaline chemistry Synthesis and biological activityrdquoHeterocycles vol 27 no 10 pp 2481ndash2515 1988

[90] S Paul and B Basu ldquoSynthesis of libraries of quinoxalinesthrough eco-friendly tandem oxidation-condensation or con-densation reactionsrdquo Tetrahedron Letters vol 52 no 49 pp6597ndash6602 2011

[91] A I Vogel A R Tatchell B S Furnis A J Hannaford andP W G Smith Vogelrsquos Textbook of Practical Organic ChemistryLongman Group London UK 1989

[92] J Frackenpohl P I Arvidsson J V Schreiber and D SeebachldquoThe outstanding biological stability of 120573- and 120574-peptidestoward proteolytic enzymes an in vitro investigation withfifteen peptidasesrdquo ChemBioChem vol 2 no 6 pp 445ndash4552001

[93] G Cardillo and C Tomasini ldquoAsymmetric synthesis of szlig-amino acids and120572-substituted120573-amino acidsrdquoChemical SocietyReviews vol 25 no 2 pp 117ndash128 1996

[94] K C Nicolaou V-M Dai and R K Guy ldquoChemistry andbiology of taxolrdquo Angewandte ChemiemdashInternational Editionvol 33 no 1 pp 15ndash44 1994

[95] F Texier-Boullet R Latouche and J Hamelin ldquoSynthesis indry media coupled with microwave irradiation application tothe preparation of 120573-aminoesters and 120573-lactams via silyl keteneacetals and aldiminesrdquo Tetrahedron Letters vol 34 no 13 pp2123ndash2126 1993

[96] E J Corey C P Decicco and R C Newbold ldquoHighly enantios-elective and diastereoselective synthesis of 120573-amino acid estersand 120573-lactams from achiral esters and iminesrdquo TetrahedronLetters vol 32 no 39 pp 5287ndash5290 1991

[97] T N Salzman R W Ratcliffe B G Christensen and F ABoufford ldquoA stereocontrolled synthesis of (+)-thienamycinrdquoJournal of the American Chemical Society vol 102 no 19 pp6161ndash6163 1980

[98] J Seyden-Penne Chiral Auxiliaries and Ligands in AsymmetricSynthesis John Wiley and Sons New York NY USA 1995

[99] B Basu P Das and I Hossain ldquoSynthesis of 120573-amino esters viaaza-Michael addition of amines to alkenes promoted on silicaa useful and recyclable surfacerdquo Synlett no 14 pp 2630ndash26322004

[100] B C Ranu S S Dey and A Hajra ldquoSolvent-free catalyst-freeMichael-type addition of amines to electron-deficient alkenesrdquoArkivoc vol 2002 no 7 pp 76ndash81 2002

[101] C Brielles J J Harnett and E Doris ldquoDiethylzincCuII-mediated alkylation of aromatic amines and related com-poundsrdquo Tetrahedron Letters vol 42 no 47 pp 8301ndash83022001


[102] D H R Barton and E Doris ldquoAlkylation of aromatic aminesand related compounds using a copper(II)-aluminum(III) cou-plerdquo Tetrahedron Letters vol 37 no 19 pp 3295ndash3298 1996

[103] S Yuvaraj V V Balasubramanian and M Palanichamy ldquoN-ethylation of aniline with ethanol or diethyl carbonate overalkali and alkaline zeolites Y and 120573rdquo Applied Catalysis A vol176 no 1 pp 111ndash117 1999

[104] D Y Yoshida and Y Tanabe ldquoDirect and selective N-monoalkynylation and N-monoalkenylation of anilines withalky(e)nyl methanesulfonates using methylmagnesium bro-mide as a baserdquo Synthesis no 5 pp 533ndash535 1997

[105] S Narayanan and K Deshpande ldquoA comparative aniline alkyla-tion activity of montmorillonite and vanadia-montmorillonitewith silica and vanadia-silicardquo Applied Catalysis A vol 135 no1 pp 125ndash135 1996

[106] P S Singh R Bandyopadhyay and B S Rao ldquoAniline methyla-tion over AEL type molecular sievesrdquo Applied Catalysis A vol136 no 2 pp 177ndash189 1996

[107] M A Aramendia V Borau C Jimenez J M Marinas andF J Romero ldquoN-alkylation of aniline with methanol overmagnesium phosphatesrdquo Applied Catalysis A vol 183 no 1 pp73ndash80 1999

[108] B L Su and D Barthbomeuf ldquoAlkylation of aniline withmethanol change in selectivity with acido-basicity of faujasitecatalystsrdquo Applied Catalysis A vol 124 no 1 pp 73ndash80 1995

[109] I I Ivanova E B Pomakhina A I Rebrov M Hunger YG Kolyagin and J Weitkamp ldquoSurface species formed duringaniline methylation on zeolite H-Y investigated by in situ MASNMR spectroscopyrdquo Journal of Catalysis vol 203 no 2 pp 375ndash381 2001

[110] K Nishamol K S Rahna and S Sugunan ldquoSelective alkylationof aniline to N-methyl aniline using chromium manganeseferrospinelsrdquo Journal of Molecular Catalysis A vol 209 no 1-2pp 89ndash96 2004

[111] K Okano H Tokuyamaand and T Fukuyama ldquoSynthesis ofsecondary arylamines through copper-mediated intermolecu-lar aryl aminationrdquo Organic Letters vol 5 no 26 pp 4987ndash4990 2003

[112] A-N Ko C-L Yang W Zhu and H Lin ldquoSelective N-alkylation of aniline with methanol over 120574-aluminardquo AppliedCatalysis A vol 134 no 1 pp 53ndash66 1996

[113] M Selva P Tundo and A Perosa ldquoReaction of primaryaromatic amines with alkyl carbonates over NaY faujasitea convenient and selective access to mono-N-alkyl anilinesrdquoJournal of Organic Chemistry vol 66 no 3 pp 677ndash680 2001

[114] B Basu S Paul andA KNanda ldquoHighly selectiveN-alkylationof amines promoted on silica an efficient and recyclablesurfacerdquo Green Chemistry vol 11 no 8 pp 1115ndash1120 2009

[115] T W Greene and P G M Wuts Protective Groups in OrganicSynthesis John Wiley and Sons New York NY USA 1999

[116] B J R Hanson Protective Groups in Organic Synthesis Black-well Science Inc Malden Mass USA 1999

[117] P A Hemsley ldquoReviews on protein acylation and micro-domains in membrane function Protein S-acylation in plants(review)rdquo Molecular Membrane Biology vol 26 pp 114ndash1252009

[118] M F G Schmidt ldquoFatty acylation of proteinsrdquo Biochimica etBiophysica Acta vol 988 no 3 pp 411ndash426 1989

[119] R Leventis G Juel J K Knudsen and J R Silvius ldquoAcyl-CoA binding proteins inhibit the nonenzymic S-acylation ofcysteinyl-containing peptide sequences by long-chain acyl-CoAsrdquo Biochemistry vol 36 no 18 pp 5546ndash5553 1997

[120] M Veit E Ponimaskin and M F G Schmidt ldquoAnalysis of s-acylation of proteinsrdquo Methods in Molecular Biology vol 446pp 163ndash182 2008

[121] H Schroeder R Leventis S Rex et al ldquoS-acylation and plasmamembrane targeting of the farnesylated carboxyl- terminalpeptide of N-ras in mammalian fibroblastsrdquo Biochemistry vol36 no 42 pp 13102ndash13109 1997

[122] F Eisele D J Owen and H Waldman ldquoPeptide conjugates astools for the study of biological signal transductionrdquo Bioorganicamp Medicinal Chemistry vol 7 no 2 pp 193ndash224 1999

[123] B Basu S Paul and A K Nanda ldquoSilica-promoted facilesynthesis of thioesters and thioethers a highly efficient reusableand environmentally safe solid supportrdquo Green Chemistry vol12 no 5 pp 767ndash771 2010

[124] K-J Soderlind B Gorodetsky A K Singh N R Bachur G GMiller and J W Lown ldquoBis-benzimidazole anticancer agentstargeting human tumour helicasesrdquo Anti-Cancer Drug Designvol 14 no 1 pp 19ndash36 1999

[125] Y Bai J Lu Z Shi and B Yang ldquoSynthesis of 215-hexa-decanedione as a precursor of musconerdquo Synlett no 4 pp 544ndash546 2001

[126] E Bouwman W L Driessen and J Reedjik ldquoModel systemsfor type I copper proteins structures of copper coordinationcompounds with thioether and azole-containing ligandsrdquoCoor-dination Chemistry Reviews vol 104 no 1 pp 143ndash172 1990

[127] M A Pujar T D Bharamgoudar and D N SathyanarayanaldquoCobalt(II) nickel(II) and copper(II) complexes of bidentatebibenzimidazolesrdquoTransitionMetal Chemistry vol 13 no 6 pp423ndash425 1988

[128] D Yang D Fokas J Li L Yu and C M Baldino ldquoAversatile method for the synthesis of benzimidazoles fromo-nitroanilines and aldehydes in one step via a reductivecyclizationrdquo Synthesis no 1 pp 47ndash56 2005

[129] R Trivedi S K De and R A Gibbs ldquoA convenient one-potsynthesis of 2-substituted benzimidazolesrdquo Journal of MolecularCatalysis A vol 245 no 1-2 pp 8ndash11 2006

[130] K Bahrami M M Khodaei and I Kavianinia ldquoA simple andefficient one-pot synthesis of 2-substituted benzimidazolesrdquoSynthesis no 4 pp 547ndash550 2007

[131] K Bahrami M Mehdi Khodaei and F Naali ldquoMild and highlyefficient method for the synthesis of 2-arylbenzimidazoles and2-arylbenzothiazolesrdquo Journal of Organic Chemistry vol 73 no17 pp 6835ndash6837 2008

[132] H Sharghi M Aberi and M M Doroodmand ldquoReusablecobalt(III)-salen complex supported on activated carbonas an efficient heterogeneous catalyst for synthesis of 2-arylbenzimidazole derivativesrdquo Advanced Synthesis and Catal-ysis vol 350 no 14-15 pp 2380ndash2390 2008

[133] Y X Chen L F Qian W Zhang and B Han ldquoEfficient aerobicoxidative synthesis of 2-substituted benzoxazoles benzothia-zoles and benzimidazoles catalyzed by 4-methoxy-TEMPOrdquoAngewandte ChemiemdashInternational Edition vol 47 no 48 pp9330ndash9333 2008

[134] D Saha A Saha and B C Ranu ldquoRemarkable influenceof substituent in ionic liquid in control of reaction simpleefficient and hazardous organic solvent free procedure for thesynthesis of 2-aryl benzimidazoles promoted by ionic liquid[pmim]BF4rdquo Green Chemistry vol 11 no 5 pp 733ndash737 2009

[135] C R C Luisa E Fernandes and M M B Marques ldquoDevel-opments towards regioselective synthesis of 12-disubstitutedbenzimidazolesrdquo ChemistrymdashA European Journal vol 17 no45 pp 12544ndash12555 2011


[136] S das Sharma and D Konwar ldquoPractical ecofriendly andchemoselectivemethod for the synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles using amberlite IR-120 as a reusable hetero-geneous catalyst in aqueous mediardquo Synthetic Communicationsvol 39 no 6 pp 980ndash991 2009

[137] K Bahrami M M Khodaei and A Nejati ldquoSynthesis of12-disubstituted benzimidazoles 2-substituted benzimidazolesand 2-substituted benzothiazoles in SDSmicellesrdquoGreenChem-istry vol 12 no 7 pp 1237ndash1241 2010

[138] J-P Wan S-F Gan J-M Wu and Y Pan ldquoWater mediatedchemoselective synthesis of 12-disubstituted benzimidazolesusing o-phenylenediamine and the extended synthesis ofquinoxalinesrdquo Green Chemistry vol 11 no 10 pp 1633ndash16372009

[139] S Das Sharma and D Konwar Synthetic Communications vol39 no 6 pp 980ndash991 2009

[140] S Santra A Majee and A Hajra ldquoNano indium oxide anefficient catalyst for the synthesis of 12-disubstituted benzim-idazoles in aqueous mediardquo Tetrahedron Letters vol 53 no 15pp 1974ndash1977 2012

[141] S Paul andB Basu ldquoHighly selective synthesis of libraries of 12-disubstituted benzimidazoles using silica gel soaked with ferricsulfaterdquo Tetrahedron Letters vol 53 no 32 pp 4130ndash4133 2012

[142] P Morys and T Schlieper ldquoSynthesis and catalytic activity ofsilica supported iron(III)rdquo Journal of Molecular Catalysis A vol95 no 1 pp 27ndash33 1995

[143] J Xu and C H Bartholomew ldquoTemperature-programmedhydrogenation (TPH) and in situMossbauer spectroscopy stud-ies of carbonaceous species on silica-supported iron Fischer-Tropsch catalystsrdquoThe Journal of Physical Chemistry B vol 109no 6 pp 2392ndash2403 2005

[144] D D E Koyuncu and S Yasyerli ldquoSelectivity and stabilityenhancement of iron oxide catalyst by Ceria Incorporation forselective oxidation of H

2S to sulfurrdquo Industrial amp Engineering

Chemistry Research vol 48 no 11 pp 5223ndash5229 2009[145] D J Kim B C Dunn F Huggins et al ldquoSBA-15-supported iron

catalysts for Fischer-Tropsch production of diesel fuelrdquo Energyand Fuels vol 20 no 6 pp 2608ndash2611 2006

[146] G A Bukhtiyarova V I Bukhtiyarov N S Sakaeva V VKaichev and B P Zolotovskii ldquoXPS study of the silica-supported Fe-containing catalysts for deep or partial H

2S

oxidationrdquo Journal of Molecular Catalysis A vol 158 no 1 pp251ndash255 2000

[147] Z Ma Y Ke H Wang et al ldquoEthylene polymerization with asilica-supported iron-based diimine catalystrdquo Journal of AppliedPolymer Science vol 88 no 2 pp 466ndash469 2003

[148] A-T Pham C Lee F M Doyle and D L Sedlak ldquoA silica-supported iron oxide catalyst capable of activating hydrogenperoxide at neutral pH valuesrdquo Environmental Science amp Tech-nology vol 43 no 23 pp 8930ndash8935 2009

[149] S Moreton ldquoSilica gel impregnated with iron(III) salts a safehumidity indicatorrdquoMaterial Research Innovations vol 5 no 5pp 226ndash229 2002


[151] M Amirnasr K J Schenk A Gorji and R VafazadehldquoSynthesis and spectroscopic characterization of [CoIII(salo-phen)(amine)

2]ClO4(amine = morpholine pyrrolidine and

piperidine) complexes The crystal structures of

[CoIII(salophen)(morpholine)2]ClO4

and [CoIII(salophen)(pyrrolidine)2]ClO

4rdquo Polyhedron vol 20 no 7-8 pp 695ndash702

2001[152] K W Pepper H M Paisley and M A Young ldquoProperties

of ion-exchange resins in relation to their structuremdashpart VIanion-exchange resins derived from styrene-divinyl-benzenecopolymersrdquo Journal of the Chemical Society pp 4097ndash41051953

[153] R V Law D C Sherrington C E Snape I Ando and HKurosu ldquoSolid-state13C MAS NMR studies of hyper-cross-linked polystyrene resinsrdquo Macromolecules vol 29 no 19 pp6284ndash6293 1996

[154] S Pickup FD BlumWT Ford andM Periyasamy ldquoTransportof small molecules in swollen polymer beadsrdquo Journal of theAmerican Chemical Society vol 108 no 14 pp 3987ndash3990 1986

[155] T Balakrishnan and W T Ford ldquoParticle size control insuspension copolymerization of styrene chloromethylstyreneand divinylbenzenerdquo Journal of Applied Polymer Science vol 27no 1 pp 133ndash138 1982

[156] R Quarrell T D Claridge G W Weaver and G LoweldquoStructure and properties of TentaGel resin beads implicationsfor combinatorial library chemistryrdquoMolecular Diversity vol 4no 4 pp 223ndash232 1996

[157] C M G Judkins K A Knights B F G Johnson Y Rde Miguel R Raja and J M Thomas ldquoImmobilisation ofruthenium cluster catalysts via novel derivatisations of ArgoGelresinsrdquo Chemical Communications no 24 pp 2624ndash2625 2001

[158] D AstrucNanoparticles and Catalysis Wiley-VCHWeinheimGermany 2008

[159] S Kobayashi and R Akiyama ldquoRenaissance of immobilizedcatalysts New types of polymer-supported catalysts lsquomicroen-capsulated catalystsrsquo which enable environmentally benignand powerful high-throughput organic synthesisrdquo ChemicalCommunications no 4 pp 449ndash460 2003

[160] S Kobayashi and R Akiyama ldquoNew methods for high-throughput synthesisrdquo Pure and Applied Chemistry vol 73 no7 pp 1103ndash1111 2001

[161] P Rylander Catalytic Hydrogenation in Organic Synthesis Aca-demic Press New York NY USA 1979

[162] N OnoTheNitro Group in Organic SynthesisWiley-VCH NewYork NY USA 2001

[163] E A Braude and R P Linstead ldquoHydrogen transfermdashpart Iintroductory surveyrdquo Journal of the Chemical Society pp 3544ndash3547 1954

[164] G Brieger and T J Nestrick ldquoCatalytic transfer hydrogenationrdquoChemical Reviews vol 74 no 5 pp 567ndash580 1974

[165] R A W Johnstone A H Wilby and I D Entwistle ldquoHet-erogeneous catalytic transfer hydrogenation and its relation toother methods for reduction of organic compoundsrdquo ChemicalReviews vol 85 no 2 pp 129ndash170 1985

[166] M Takasaki Y Motoyama K Higashi S-H Yoon IMochida and H Nagashima ldquoChemoselective hydrogenationof nitroarenes with carbon nanofiber-supported platinum andpalladium nanopraticlesrdquo Organic Letters vol 10 no 8 pp1601ndash1604 2008

[167] S K Mohapatra S U Sonavane R V Jayaram and P SelvamldquoHeterogeneous catalytic transfer hydrogenation of aromaticnitro and carbonyl compounds over cobalt(II) substitutedhexagonal mesoporous aluminophosphate molecular sievesrdquoTetrahedron Letters vol 43 no 47 pp 8527ndash8529 2002


[168] R V Jagadeesh G Wienhofer F A Westerhaus et al ldquoEfficientand highly selective iron-catalyzed reduction of nitroarenesrdquoChemical Communications vol 47 no 39 pp 10972ndash10974 2011

[169] A Saha and B C Ranu ldquoHighly chemoselective reduc-tion of aromatic nitro compounds by copper nanoparti-clesammonium formaterdquo The Journal of Organic Chemistryvol 73 no 17 pp 6867ndash6870 2008

[170] R J Rahaim Jr and R E Maleczka Jr ldquoPd-catalyzed siliconhydride reductions of aromatic and aliphatic nitro groupsrdquoOrganic Letters vol 7 no 22 pp 5087ndash5090 2005

[171] K Nomura ldquoEfficient selective reduction of aromatic nitrocompounds by rutheniumcatalysis underCOH

2Oconditionsrdquo

Journal ofMolecular Catalysis A vol 95 no 3 pp 203ndash210 1995[172] L He L-C Wang H Sun et al ldquoEfficient and selective room-

temperature gold-catalyzed reduction of nitro compounds withCO and H

2O as the hydrogen sourcerdquo Angewandte Chemiemdash

International Edition vol 48 no 50 pp 9538ndash9541 2009[173] R V Niquirilo E Teixeira-Neto G S Buzzo and H B

Suffredini ldquoFormic acid oxidation at Pd Pt and PbOx-basedcatalysts and calculation of their approximate electrochemicalactive areasrdquo International Journal of Electrochemical Sciencevol 5 no 3 pp 344ndash354 2010

[174] B Basu M M H Bhuiyan P Das and I Hossain ldquoCatalytictransfer reduction of conjugated alkenes and an imine usingpolymer-supported formatesrdquo Tetrahedron Letters vol 44 no50 pp 8931ndash8934 2003

[175] N A Cortese and R F Heck ldquoPalladium catalyzed reductionsof halo- and nitroaromatic compoundswith triethylammoniumformaterdquo The Journal of Organic Chemistry vol 42 no 22 pp3491ndash3494 1977

[176] HWeiner J Blum andY Sasson ldquoStudies on themechanism oftransfer hydrogenation of nitro arenes by formate salts catalyzedby palladiumcarbonrdquoThe Journal of Organic Chemistry vol 56no 14 pp 4481ndash4486 1991

[177] D C Gowda A S P Gowda A R Baba and S Gowda ldquoNickel-catalyzed formic acid reductions A selective method for thereduction of nitro compoundsrdquo Synthetic Communications vol30 no 16 pp 2889ndash2895 2000

[178] K Hanaya T Muramatsu H Kudo and Y L Chow ldquoReduc-tion of aromatic nitro-compounds to amines with sodiumborohydride-copper(II) acetylacetonaterdquo Journal of the Chem-ical Society Perkin Transactions 1 pp 2409ndash2410 1979

[179] N Pradhan A Pal and T Pal ldquoSilver nanoparticle catalyzedreduction of aromatic nitro compoundsrdquo Colloids and SurfacesA vol 196 no 2-3 pp 247ndash257 2002

[180] B Basu P Das and S Das ldquoTransfer hydrogenation usingrecyclable polymer-supported formate (PSF) efficient andchemoselective reduction of nitroarenesrdquo Molecular Diversityvol 9 no 4 pp 259ndash262 2005

[181] P Selvam S K Mohapatra S U Sonavane and R V JayaramldquoChemo- and regioselective reduction of nitroarenes carbonylsand azo dyes over nickel-incorporated hexagonal mesoporousaluminophosphate molecular sievesrdquo Tetrahedron Letters vol45 no 9 pp 2003ndash2007 2004

[182] S K Mohapatra S U Sonavane R V Jayaram and P SelvamldquoReductive cleavage of azo dyes and reduction of nitroarenesover trivalent iron incorporated hexagonal mesoporous alu-minophosphate molecular sievesrdquo Applied Catalysis B vol 46no 1 pp 155ndash163 2003

[183] S K Mohapatra S U Sonavane R V Jayaram and P SelvamldquoHeterogeneous catalytic transfer hydrogenation of aromatic

nitro and carbonyl compounds over cobalt(II) substitutedhexagonal mesoporous aluminophosphate molecular sievesrdquoTetrahedron Letters vol 43 no 47 pp 8527ndash8529 2002

[184] S K Mohapatra S U Sonavane R V Jayaram and P SelvamldquoRegio- and chemoselective catalytic transfer hydrogenation ofaromatic nitro and carbonyl as well as reductive cleavage ofazo compounds over novel mesoporous NiMCM-41 molecularsievesrdquo Organic Letters vol 4 no 24 pp 4297ndash4300 2002

[185] A S Kulkarni andRV Jayaram ldquoLiquid phase catalytic transferhydrogenation of aromatic nitro compounds on perovskitesprepared by microwave irradiationrdquo Applied Catalysis A vol252 no 2 pp 225ndash230 2003

[186] A S Kulkarni andRV Jayaram ldquoLiquid phase catalytic transferhydrogenation of aromatic nitro compounds on La

1minus119909Sr119909FeO3

perovskites prepared by microwave irradiationrdquo Journal ofMolecular Catalysis A vol 223 pp 107ndash110 2004

[187] B Basu B Mandal S Das P Das and A K Nanda ldquoChemos-elective reduction of aldehydes by ruthenium trichloride andresin-bound formatesrdquo The Beilstein Journal of Organic Chem-istry vol 4 no 53 2008

[188] B Basu S Das P Das and A K Nanda ldquoCo-immobilizedformate anion and palladium on a polymer surface a novelheterogeneous combination for transfer hydrogenationrdquo Tetra-hedron Letters vol 46 no 49 pp 8591ndash8593 2005

[189] E-I NegishiOrganopalladiumChemistry for Organic SynthesisWiley-InterScience New York NY USA 2002

[190] A DMeijere and F DiederichMetal-Catalyzed Cross-CouplingReactions Wiley-VCH Weinheim Germany 2004

[191] C C Mauger and G A Mignani ldquoSynthetic applications ofBuchwaldrsquos phosphines in palladium-catalyzed aromatic-bond-forming reactionsrdquo Aldrichimica Acta vol 39 no 1 pp 17ndash242006

[192] W A Herrmann K Ofele D V Preysing and S K SchneiderldquoPhospha-palladacycles and N-heterocyclic carbene palladiumcomplexes efficient catalysts for CC-coupling reactionsrdquo Jour-nal of Organometallic Chemistry vol 687 no 2 pp 229ndash2482003

[193] L Yin and J Liebscher ldquoCarbon-carbon coupling reactionscatalyzed by heterogeneous palladium catalystsrdquo ChemicalReviews vol 107 no 1 pp 133ndash173 2007

[194] K Sonogashira Y Tohda and N Hagihara ldquoA convenientsynthesis of acetylenes catalytic substitutions of acetylenichydrogenwith bromoalkenes iodoarenes and bromopyridinesrdquoTetrahedron Letters vol 16 no 50 pp 4467ndash4470 1975

[195] K Sonogashira ldquoCoupling reactions between sp2 and sp carboncentersrdquo in Comprehensive Organic Synthesis B M Trost Edvol 3 pp 521ndash549 Pergamon Press Oxford UK 1999

[196] C J SWuMDWatson L Zhang Z HWang and KMullenldquoHexakis(4-iodophenyl)-peri-hexabenzocoronenemdasha versatilebuilding block for highly ordered discotic liquid crystallinematerialsrdquo Journal of the American Chemical Society vol 126no 1 pp 177ndash186 2004

[197] G Hennrich and A M Echavarren ldquoNew persubstituted 135-trisethynyl benzenes via Sonogashira couplingrdquo TetrahedronLetters vol 45 no 6 pp 1147ndash1149 2004

[198] J N Wilson M Josowicz Y Q Wang and U H F Bunz ldquoCru-ciform 120587-systems hybrid phenylene-ethynylenephenylene-vinylene oligomersrdquo Chemical Communications no 24 pp2962ndash2963 2003

[199] C C Li Z X Xie Y D Zhang J H Chen and Z Yang ldquoTotalsynthesis of wedelolactonerdquo The Journal of Organic Chemistryvol 68 no 22 pp 8500ndash8504 2003


[200] K Y Tsang M A Brimble and J B Bremner ldquoUse of asonogashira-acetylide coupling strategy for the synthesis of thearomatic spiroketal skeleton of 120574-rubromycinrdquo Organic Lettersvol 5 no 23 pp 4425ndash4427 2003

[201] I Paterson R D M Davies A L Heimann R Maquez and AMeyer ldquoStereocontrolled total synthesis of (minus)-callipeltoside ArdquoOrganic Letters vol 5 no 23 pp 4477ndash4480 2003

[202] J W Lane and R L Halcomb ldquoA new method for the stereose-lective synthesis of 120572-substituted serine amino acid analoguesrdquoOrganic Letters vol 5 no 22 pp 4017ndash4020 2003

[203] T M Hansen M M Engler and C J Forsyth ldquoTotal synthesisof a biotinylated derivative of phorboxazole A via sonogashiracouplingrdquo Bioorganic ampMedicinal Chemistry Letters vol 13 no13 pp 2127ndash2130 2003

[204] N Ohyaba T Nishkawa and M Isobe ldquoFirst asymmetric totalsynthesis of tetrodotoxinrdquo Journal of the American ChemicalSociety vol 125 no 29 pp 8798ndash8805 2003

[205] J A Marshall and G M Schaaf ldquoTotal synthesis and structureconfirmation of leptofuranin Drdquo Journal of Organic Chemistryvol 68 no 19 pp 7428ndash7432 2003

[206] S Lopez F Fernandeztrillo L Castedo and C Saa ldquoSynthesisof callyberynes A and B polyacetylenic hydrocarbons frommarine spongesrdquo Organic Letters vol 5 no 20 pp 3275ndash37282003

[207] D W C MacMillan ldquoThe advent and development oforganocatalysisrdquo Nature vol 455 no 7211 pp 304ndash308 2008

[208] S Kobayashi and K Manabe ldquoDevelopment of novel Lewisacid catalysts for selective organic reactions in aqueous mediardquoAccounts of Chemical Research vol 35 no 4 pp 209ndash217 2002

[209] H C Kolb M G Finn and K B Sharpless ldquoClick chemistrydiverse chemical function from a few good reactionsrdquo Ange-wandte ChemiemdashInternational Edition vol 40 no 11 pp 2004ndash2021 2001

[210] S R Chemler D Trauner and S J Danishefsky ldquoThe b-alkylSuzuki-Miyaura cross-coupling reaction development mech-anistic study and applications in natural product synthesisrdquoAngewandte ChemiemdashInternational Edition vol 40 no 24 pp4544ndash4568 2001

[211] NMiyaura ldquoSynthesis of biaryls via the cross-coupling reactionof arylboronic acidsrdquoAdvances inMetal-Organic Chemistry vol6 pp 187ndash243 1998

[212] L F Tietze G Kettschau U Heuschert and G NordmanldquoHighly efficient synthesis of linear pyrrole oligomers bytwofold Heck reactionsrdquo ChemistrymdashA European Journal vol7 no 2 pp 368ndash373 2001

[213] S Kotha K Lahiri and D Kashinath ldquoRecent applications ofthe Suzuki-Miyaura cross-coupling reaction in organic synthe-sisrdquo Tetrahedron vol 58 no 48 pp 9633ndash9695 2002

[214] D Alberico M E Scott and M Lautens ldquoAryl-aryl bond for-mation by transition-metal-catalyzed direct arylationrdquo Chemi-cal Reviews vol 107 no 1 pp 174ndash238 2007

[215] I P Beletskaya and A V Cheprakov ldquoHeck reaction as asharpening stone of palladium catalysisrdquoChemical Reviews vol100 no 8 pp 3009ndash3066 2000

[216] K C Nicolaou H Li C N C Boddy et al ldquoTotal synthesis ofvancomycinmdashpart 1 design and development of methodologyrdquoChemistrymdashA European Journal vol 5 no 9 pp 2584ndash26011999

[217] K Kamikawa T Watanabe A Daimon and M UemuraldquoStereoselective synthesis of axially chiral natural products(-)-steganone and OO1015840-dimethylkorupensamine A utilizing

planar chiral (arene)chromium complexesrdquo Tetrahedron vol56 no 15 pp 2325ndash2337 2000

[218] A Haberli and C J Leumann ldquoSynthesis of pyrrolidine C-nucleosides via heck reactionrdquo Organic Letters vol 3 no 3 pp489ndash492 2001

[219] httpwwwnobelprizeorg[220] C Ramarao S V Ley S C Smith I M Shirley and N D

Almerda ldquoEncapsulation of palladium in polyurea microcap-sulesrdquo Chemical Communications no 10 pp 1132ndash1133 2002

[221] J Q Yu H C Wu C Ramarao J B Spencer and SV Ley ldquoTransfer hydrogenation using recyclable polyurea-encapsulated palladium efficient and chemoselective reductionof aryl ketonesrdquo Chemical Communications no 6 pp 678ndash6792003

[222] S V Ley C Mitchell D Pears C Ramarao J-Q Yu and WZhou ldquoRecyclable polyurea-microencapsulated Pd(0) nanopar-ticles an efficient catalyst for hydrogenolysis of epoxidesrdquoOrganic Letters vol 5 no 24 pp 4665ndash4668 2003

[223] V Chechik and R M Crooks ldquoDendrimer-encapsulated Pdnanoparticles as fluorous phase-soluble catalystsrdquo Journal of theAmerican Chemical Society vol 122 no 6 pp 1243ndash1244 2000

[224] S Kobayashi and S Nagayama ldquoA microencapsulated Lewisacid a new type of polymer-supported Lewis acid catalystof wide utility in organic synthesisrdquo Journal of the AmericanChemical Society vol 120 no 12 pp 2985ndash2986 1998

[225] S KobayashiM Endo and SNagayama ldquoCatalytic asymmetricdihydroxylation of olefins using a recoverable and reusablepolymer-supported osmium catalystrdquo Journal of the AmericanChemical Society vol 121 no 48 pp 11229ndash11230 1999

[226] R Akiyama and S Kobayashi ldquoMicroencapsulated palladiumcatalysts allylic substitution and Suzuki coupling using a recov-erable and reusable polymer-supported palladium catalystrdquoAngewandte ChemiemdashInternational Edition vol 40 no 18 pp3469ndash3471 2001

[227] R Akiyama and S Kobayashi ldquoA novel polymer-supportedarene-ruthenium complex for ring-closing olefin metathesisrdquoAngewandte ChemiemdashInternational Edition vol 41 no 14 pp2602ndash2604 2002

[228] R Akiyama and S Kobayashi ldquoThe polymer incarceratedmethod for the preparation of highly active heterogeneouspalladium catalystsrdquo Journal of the American Chemical Societyvol 125 no 12 pp 3412ndash3413 2003

[229] K Okamota R Akiyama and S Kobayashi ldquoRecoverablereusable highly active and sulfur-tolerant polymer incarcer-ated palladium for hydrogenationrdquo The Journal of OrganicChemistry vol 69 pp 2871ndash2873 2004

[230] K Okamota R Akiyama and S Kobayashi ldquoSuzuki-Miyauracoupling catalyzed by polymer-incarcerated palladium a highlyactive recoverable and reusable Pd catalystrdquo Organic Lettersvol 6 no 12 pp 1987ndash1990 2004

[231] L K Okamota R Akiyama H Yoshida T Yoshida and SKobayashi ldquoFormation of nanoarchitectures including sub-nanometer palladium clusters and their use as highly activecatalystsrdquo Journal of the American Chemical Society vol 127 no7 pp 2125ndash2135 2005

[232] H Hagio M Sugiura and S Kobayashi ldquoPractical preparationmethod of polymer-incarcerated (PI) palladium catalysts usingPd(II) saltsrdquo Organic Letters vol 8 no 3 pp 375ndash378 2006

[233] L Strimbu J Liu and A E Kaifer ldquoCyelodextrin-cappedpalladium nanoparticles as catalysts for the Suzuki reactionrdquoLangmuir vol 19 no 2 pp 483ndash485 2003


[234] E H Rahim F S Kamounah J Frederiksen and J BChristensen ldquoHeck reactions catalyzed by PAMAM-dendrimerencapsulated Pd(0) nanoparticlesrdquoNano Letters vol 1 no 9 pp499ndash501 2001

[235] M Pittelkow K Moth-Poulsen U Boas and J B ChristensenldquoPoly(amidoamine)-dendrimer-stabilized Pd(0) nanoparticlesas a catalyst for the Suzuki reactionrdquo Langmuir vol 19 no 18pp 7682ndash7684 2003

[236] J C Garcia-Martinez R Lezutekong and R M CrooksldquoDendrimer-encapsulated Pd nanoparticles as aqueous room-temperature catalysts for the Stille reactionrdquo Journal of theAmerican Chemical Society vol 127 no 14 pp 5097ndash5103 2005

[237] D Basu S Das P Das B Mandal D Banerjee and F AlmqvistldquoPalladium supported on a polyionic resin as an efficientligand-free and recyclable catalyst for Heck Suzuki-Miyauraand Sonogashira reactionsrdquo Synthesis no 7 pp 1137ndash1146 2009

[238] A Kirschning H Monenschein and R Wittenberg ldquoTheldquoresin-capture-releaserdquo hybrid technique a merger betweensolid- and solution-phase synthesisrdquo ChemistrymdashA EuropeanJournal vol 6 no 24 pp 4445ndash4450 2000

[239] httpwwwcypress-internationalcomimagepolymerlabspldmappdf

[240] S Khound and P J Das ldquoSolid phase synthesis of N-aryl-azoindolesrdquo Tetrahedron vol 53 no 28 pp 9749ndash9754 1997

[241] S Roller H Turk J-F Stumbe W Rapp and R HaagldquoPolystyrene-graft-polyglycerol resins a new type of high-loading hybrid support for organic synthesisrdquo Journal of Com-binatorial Chemistry vol 8 no 3 pp 350ndash354 2006

[242] Y Zheng P D Stevens and Y Gao ldquoMagnetic nanoparticles asan orthogonal support of polymer resins applications to solid-phase suzuki cross-coupling reactionsrdquo The Journal of OrganicChemistry vol 71 no 2 pp 537ndash542 2006

[243] T E Nielsen S Le Quement and M Meldal ldquoSolid-phase synthesis of biarylalanines via Suzuki cross-couplingand intramolecular N-acyliminium Pictet-Spengler reactionsrdquoTetrahedron Letters vol 46 no 46 pp 7959ndash7962 2005

[244] J F Brown P Krajnc and N R Cameron ldquoPolyHIPE supportsin batch and flow-through suzuki cross-coupling reactionsrdquoIndustrial amp Engineering Chemistry Research vol 44 no 23 pp8565ndash8572 2005

[245] J T Bork J W Lee and Y-T Chang ldquoPalladium-catalyzedcross-coupling reaction of resin-bound chlorotriazinesrdquo Tetra-hedron Letters vol 44 no 32 pp 6141ndash6144 2003

[246] J V Wade and C A Krueger ldquoSuzuki cross-coupling of solid-supported chloropyrimidineswith arylboronic acidsrdquo Journal ofCombinatorial Chemistry vol 5 no 3 pp 267ndash272 2003

[247] A Hebel and R Haag ldquoPolyglycerol as a high-loading supportfor boronic acids with application in solution-phase Suzukicross-couplingsrdquo Journal of Organic Chemistry vol 67 no 26pp 9452ndash9455 2002

[248] GWulffH SchmidtHWitt andR Zentel ldquoCooperativity andtransfer of chirality in liquid-crystalline polymersrdquoAngewandteChemiemdashInternational Edition vol 33 no 2 pp 188ndash191 1994

[249] J W Guiles S G Johnson and W V Murray ldquoSolid-phaseSuzuki coupling for C-C bond formationrdquo Journal of OrganicChemistry vol 61 no 15 pp 5169ndash5171 1996

[250] S R Piettre and S Baltzer ldquoA new approach to the solid-phaseSuzuki coupling reactionrdquo Tetrahedron Letters vol 38 no 7 pp1197ndash1200 1997

[251] R J Kell P Hodge M Nisar and R T Williams ldquoFacileattachment of functional moieties to crosslinked polystyrene

beads via robust linkages Suzuki reactions using polymer-supported boronic acidsrdquo Journal of the Chemical Society PerkinTransactions 1 no 24 pp 3403ndash3408 2001

[252] Y Han S D Walker and R N Young ldquoSilicon directedipso-substitution of polymer bound arylsilanes preparation ofbiaryls via the Suzuki cross-coupling reactionrdquo TetrahedronLetters vol 37 no 16 pp 2703ndash2706 1996

[253] V Lobregat G AlcarazH Bienayme andMVaultier ldquoApplica-tion of the lsquoresin-capture-releasersquo methodology to macrocycli-sation via intramolecular Suzuki-Miyaura couplingrdquo ChemicalCommunications no 9 p 817 2001

[254] M J Farrall and J M J Frechet ldquoBromination and lithiationtwo important steps in the functionalization of polystyreneresinsrdquo The Journal of Organic Chemistry vol 41 no 24 pp3877ndash3882 1976

[255] R Frenette and R W Friesen ldquoBiaryl synthesis via suzukicoupling on a solid supportrdquo Tetrahedron Letters vol 35 no 49pp 9177ndash9180 1994

[256] B Basu S Das S Kundu and B Mandal ldquoPolyionic heteroge-neous phenylating agent for base-free Suzuki-Miyaura couplingreactionrdquo Synlett no 2 pp 255ndash259 2008

[257] D C Jocelyn Biochemistry of the Thiol Group Academic PressNew York NY USA 1992

[258] M Bodzansky Principles of Peptide Synthesis chapter 4Springer Berlin Germany 1984

[259] G Capozzi and G Modena ldquoOxidation of thiolrdquo in TheChemistry of the Thiol Group Part II S Patai Ed p 785 JohnWiley and Sons New York NY USA 1975

[260] K Inaba ldquoDisulfide bond formation system in Escherichia colirdquoJournal of Biochemistry vol 146 no 5 pp 591ndash597 2009

[261] W J Wedemeyer E Welker M Narayan and H A ScheragaldquoDisulfide bonds and protein foldingrdquo Biochemistry vol 39 no15 pp 4207ndash4216 2000

[262] K Ramadas and N Srinivasan ldquoSodium chloritemdashyet anotheroxidant for thiols to disulphidesrdquo Synthetic Communicationsvol 25 no 2 pp 227ndash234 1995

[263] H L Fisher ldquoElastomersrdquo Industrial amp Engineering Chemistryvol 42 no 10 pp 1978ndash1982 1950

[264] D Sengupta and B Basu ldquoAn efficient metal-free synthesisof organic disulfides from thiocyanates using poly-ionic resinhydroxide in aqueousmediumrdquo Tetrahedron Letters vol 54 no18 pp 2277ndash2281 2013

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Inorganic oxidesandor doped

inorganic oxide

KF-alumina

Silica orFe(III)-silica

Pd-catalyzed

Pd-catalyzed

alkylations

S-acylation

Quinoxaline synthesis

Aza-Michaeladdition

Selective benzimidazole

synthesis

CndashC couplings

CndashN coupling

N- or S-

Figure 1

Towards developing new organic reactions and catalysisour group has primarily employed two categories of poly-mers (i) inorganic oxides either directly or having dopedwith some other inorganic salts and (ii) polyionic resinsto immobilize reagentsmetal nanoparticles (NPs) as thesolid-phase catalysts or heterogeneous nanocatalysts Thisreview article will primarily focus on our efforts vis-a-vismentioning notable and relevant achievements from otherresearch groups The subject has been organized accordingto nature of the target molecules to synthesize nature ofreaction and also the type of solid supports employed invarious reactions

Figure 1 illustrates examples of our efforts towards thesynthesis of CndashC and CndashX (heteroatom) bond-formingreactions and synthesis of libraries of small heterocyclicmolecules of biological importance having promoted orcatalyzed on commercially available silica gel alumina ordoped with iron(III) salt or potassium fluoride respectively

2 KFAlumina MediatedCatalyzedOrganic Reactions

Commercially available alumina (Al2O3) is known to catalyze

or promote a variety of organic transformations [2 51] How-ever alumina doped with potassium fluoride (KFalumina)has been extensively used as solid basic surface in vast rangeof organic transformation [52] since it was introduced byAndo et al [53ndash56] Alumina doped with KF can ionizeC-acids up to pKa sim35 [57] Although the actual basicsite developed on the surface on alumina is dependent oftemperature and partially debatable the 19F magic angleNMR and IR spectroscopic measurements have shown thatthe fluoride anion species inKFalumina ismore electron richthan fluoride anion in pure solid The conditions of loadingof KF seem to be critical to its functioning and displayingvarying properties

21 Buchwald-Hartwig CndashN Cross-Coupling Reaction Thefirst reaction was studied on the surface of KFalumina is theBuchwald-Hartwig CndashN cross-coupling reactions betweenaryl halides and an amine Initial independent reports by

Buchwald and Hartwig clearly noticed that the success ofsuch coupling is tricky to the use of the base and sodium orpotassium tert-butoxide was found to be best for such CndashNcross-coupling reactions [58ndash61] Secondly initial conditionswere not successful for heteroaryl substrates possibly becauseof formation of stable palladium complex that does notfurther participate in the catalytic cycle Buchwald howevercircumvented this problem by using chelating ligands so asto avoid formation of substrate-based palladium complexes[62]

Palladium-catalyzed CndashN hetero cross-coupling reac-tions between bromopyridines and amines (both primaryand secondary) can be efficiently performed on aKFalumina(basic) surface (Scheme 1) thus negating the use of strongbases such as sodium tert-butoxide The reaction conditionshave been optimized with reference to catalytic systemssolvents and the surface A variety of phosphines both asmono- and bisphosphine ligands are found to be equallyactive [63]

To broaden the scope of this CndashN hetero cross-couplingthe reaction protocol has been extended to haloaromaticsThe reactions are not only found to be applicable to bro-moarenes but also offer high selectivity in cross-coupling ofpolyhaloaromatics Indeed there has been high selectivitybetween mono- or polyaminations (bis- tris- or tetra-)depending on the proportion of KF and alumina [64] Higherproportion of KF and slight higher temperature can lead topolyamination while lower amount of KF in KFaluminagenerally affords only monoaminated product (Scheme 2)

Notable features of the use of KF doped with alumina(KFalumina) are (i) the use of NaOBu119905 can be avoided(ii) conditions are not ligand-specific (iii) solvent-free reac-tions generally give better yields (iv) applicable to bothbromoarenes and N-heteroaryl bromides (v) varying pro-portions of KF per gram of alumina offer selectivity and (vi)recycling of the solid surface is possible

22 DoubleMichael Addition TheMichael addition reactionan important CndashC bond-forming reaction is known to pro-duce adducts which have found wide synthetic applications[65ndash68] Several acidic and basic catalysts are used to affectthis conjugate addition reaction Side reactions frequentlyencountered in the presence of a base catalyst are secondarycondensations polymerizations and double additions How-ever the reactions in which two CndashC bonds are selectivelyformed by intermolecular and consecutive double Michaelreactions in one-pot are very rare It was observed thatKFalumina can promote consecutive Michael additions ofthe nucleophile derived from acetophenone to electron defi-cient alkenes Thus an efficient and highly selective one-potprocedure for the double Michael reactions was developedleading to the formation of pimelate ester derivatives [69]This is the first example of selective double Michael additionsof aromatic and aliphaticmethyl ketones to electron-deficientalkenes mediated over KFalumina (Scheme 3)

Both aliphatic and aromatic ketones underwent bis-addition with similar efficiencies and afforded the desiredproducts Mixture of acetone and ethyl acrylate yielded the


N

Br

X

X = H Br alkyl

Pd catligand

KFalumina (14)+

N

X

N O

O+

Br

N

N O

OR R

LigandKFalumina

R2NHor

RNH2

NHR or NR2

(48ndash91)

(62ndash73)


X = H NR2 alkyl

Scheme 1

Br

Brn

Brn

+

n

NR2

NR2


n = 1 2 3

R2NH

(gt80) (70ndash85)

NR2


Scheme 2

OCOOEt KFalumina

O

COOEt

COOEt

O

COOEt

67 8

CH3

50∘C 10 h

+ +

OCOOEt KFalumina

O

COOEt

COOEt63

+CH3H3C 40∘C 12 h H3C

Ph KFalumina

75

O O Ph

+CH3


Scheme 3






Xn


MW

n

X XX = Br or I



Scheme 4







KFaluminaMW

Ph4BNaor

PhB(OH)2R1NH2

Cu(OAC)2

R1 = Alkyl or aryl

NHR1

+

Scheme 5





HO

ON

N

OBr

N

N

O

O

N

N

+ KFalumina

NH2

NH2

R1

R2

R2

R2

R3

R2

R2

R2

R2

R2

R3

R1

R1

R1




Scheme 6

N HSilica gel N

SH

COOEtHN

S

COOEtCOOEt

88Silica gel

R2

R1 R3


1ndash12 hR2

R1

R3

(50ndash99)

NH2

40ndash70∘C+

+12h70∘C

Scheme 7







R X(1 Equiv)

R X(22 Equiv)


R RN

H


Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2



Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R


RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2


Scheme 9











CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


N

Br

X

X = H Br alkyl

Pd catligand

KFalumina (14)+

N

X

N O

O+

Br

N

N O

OR R

LigandKFalumina

R2NHor

RNH2

NHR or NR2

(48ndash91)

(62ndash73)


X = H NR2 alkyl

Scheme 1

Br

Brn

Brn

+

n

NR2

NR2


n = 1 2 3

R2NH

(gt80) (70ndash85)

NR2


Scheme 2

OCOOEt KFalumina

O

COOEt

COOEt

O

COOEt

67 8

CH3

50∘C 10 h

+ +

OCOOEt KFalumina

O

COOEt

COOEt63

+CH3H3C 40∘C 12 h H3C

Ph KFalumina

75

O O Ph

+CH3


Scheme 3






Xn


MW

n

X XX = Br or I



Scheme 4







KFaluminaMW

Ph4BNaor

PhB(OH)2R1NH2

Cu(OAC)2

R1 = Alkyl or aryl

NHR1

+

Scheme 5





HO

ON

N

OBr

N

N

O

O

N

N

+ KFalumina

NH2

NH2

R1

R2

R2

R2

R3

R2

R2

R2

R2

R2

R3

R1

R1

R1




Scheme 6

N HSilica gel N

SH

COOEtHN

S

COOEtCOOEt

88Silica gel

R2

R1 R3


1ndash12 hR2

R1

R3

(50ndash99)

NH2

40ndash70∘C+

+12h70∘C

Scheme 7







R X(1 Equiv)

R X(22 Equiv)


R RN

H


Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2



Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R


RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2


Scheme 9











CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Xn


MW

n

X XX = Br or I



Scheme 4







KFaluminaMW

Ph4BNaor

PhB(OH)2R1NH2

Cu(OAC)2

R1 = Alkyl or aryl

NHR1

+

Scheme 5





HO

ON

N

OBr

N

N

O

O

N

N

+ KFalumina

NH2

NH2

R1

R2

R2

R2

R3

R2

R2

R2

R2

R2

R3

R1

R1

R1




Scheme 6

N HSilica gel N

SH

COOEtHN

S

COOEtCOOEt

88Silica gel

R2

R1 R3


1ndash12 hR2

R1

R3

(50ndash99)

NH2

40ndash70∘C+

+12h70∘C

Scheme 7







R X(1 Equiv)

R X(22 Equiv)


R RN

H


Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2



Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R


RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2


Scheme 9











CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


HO

ON

N

OBr

N

N

O

O

N

N

+ KFalumina

NH2

NH2

R1

R2

R2

R2

R3

R2

R2

R2

R2

R2

R3

R1

R1

R1




Scheme 6

N HSilica gel N

SH

COOEtHN

S

COOEtCOOEt

88Silica gel

R2

R1 R3


1ndash12 hR2

R1

R3

(50ndash99)

NH2

40ndash70∘C+

+12h70∘C

Scheme 7







R X(1 Equiv)

R X(22 Equiv)


R RN

H


Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2



Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R


RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2


Scheme 9











CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


R X(1 Equiv)

R X(22 Equiv)


R RN

H


Cl Ph ClNHCl

PhNCl

PhSilica gel80 70

Silica gel

R1R1 R1NH2

NH2



Scheme 8

R SH

(15 Equiv)CO

X

X X

O O

(04 Equiv)

SRO

S S

O ORR

Silica gelRT

X(12 Equiv)

S S

(04 Equiv)

X X

S R


RR

R1R1

(05ndash10) h

R2 R2

(4ndash18) h

n

nn

n

n = 2n = 2


Scheme 9











CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


CHON

NNH

N

1 3 42 5

N

NNH2

NH2

R1R2 R1 R2

R2

R2

R1

R2

R1 R2+ + +

Scheme 10

CHO

1 32

N


Rt

NH2

NH2

R1 R2 R2

R2

R1+

Scheme 11

2 PhCHON

N

Ph

HHPh

N

NPh

Ph

N

N HPh

H

Ph

FeHO

SiOH

FeHO

SiOH

FeHO

SiOH

(5)(4)

(3)

NH2

NH2

+

+

∙ ∙

∙ ∙

Figure 2

OHC

HO

N

N

OH

HO


N

No-OH

o -OH


(6)NH2

NH2

C6H4

C6H4

90∘C 15 h 90

∘C 15 h

30∘C

+

Scheme 12







O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

PhPhPhX

Ph PhPh+ +

Styrenemonomer



Radicalinitiator

2

Polystyrenechain

Crosslink


Figure 3

OO

Xn

TentaGel

PS

ArgoGel

PS

Me

O

OO

OX

X

m

n

n = 70

X = OH or NH2

X = OH NH2 Cl

Figure 4






2and (aminomethyl)








HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


HCOO

N

HN

O

HR

Cat

OH

HRH

ARF

R

R

O

O

R

R O

R

R

OH

Pd cat

Pd catPd cat

Pd cat

NR3

R2

R1

R2

R1

R2

R1

R3

R3

R3

R4

R2

R1 R3

R4

RuCl3

NO2

NH2

+

minus

Figure 5

XHCOO

X

Cl

Aq HCOOH

(10 vv)



NR3

+minus

HCOO NR3NR3

++minusminus

R2 R2

R1 R3R1 R3

R4 R4


Scheme 13

HCOONO2

R1

NR3


NH2

R1

Scheme 14







OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


OO

OH

OH

R

O

O

R

R

O

OH

R

R = H 87R = Me 90R = OMe 87

R1 R1

R2 R2

NR3



(70ndash96)



+minus

DMF90∘C12 h

Scheme 15

OO

O

H

OPd

Pd HPd H

CO2

Scheme 16

+

+Stirring at RT

Pd (0)HCOO

DMF+

HCOONR3minus

Pd (OAc)2or

Na2PdCl4

NR3

minus

Scheme 17














ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


ARF-PdDMF

R

O

O

R

R

O

OH

R

ARF-PdDMF

X XHARF-PdDMF

110∘C

110∘C

NO2

R1

NH2

R1


50ndash80∘C

R1

R2

R3

R4

R1

R2

R3

R4

(gt85)

(gt80)

Scheme 18

R+

X

(-HX)

R

BOH

OH

+

XPd-Catalyst

Base

I +

Pd(PPh3)4 base

R1

R1

R2

R2

R1(PPh3)2PdCl2

CuI R3N

R1

Scheme 19


2as the source of
















2 2mol and




2CO3afforded


4 the



O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

RI

R +ARF-PdDMF

O

O

Br

ARF-Pd+

I + HARF-Pd



OCH3

CH3

B(OH)2

H3CO

H3C

R3R3

Et3N CH3CN

R2

R1

R2

R1

R1 R2 = OMe Me Br


Scheme 20

Me I

I

II

III

or+

Me PhNR3BPh4

NaBPh4

Pd(OAc)2(2 mol)

85∘C 2 h

Conditions

minus+


Scheme 21




3 K2CO3[264]

5 Conclusion



R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


R SCNor

Ar

OSCN


or

Ar

OS

2




Scheme 22

Acknowledgments


References



























































































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of
























































































































2S


































2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






2Oconditionsrdquo

















































































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of















































































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

solid-phase organic synthesis and catalysis: some recent

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