research article sulfonic acid functionalized nano- -al o a new,...

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 838374 6 pageshttpdxdoiorg1011552013838374

Research ArticleSulfonic Acid Functionalized Nano-120574-Al2O3A New Efficient and Reusable Catalyst for Synthesis of3-Substituted-2H-14-Benzothiazines

Wei Lin Li1 Shuan Bao Tian2 and Feng Zhu3

1 Department of Medicinal Chemistry Pharmacy College of Xinxiang Medical University Xinxiang 453003 China2 School of Basic Medical Sciences Xinxiang Medical University Xinxiang 453003 China3Department of Urology The First Affiliated Hospital of Xinxiang Medical University Xinxiang 453003 China

Correspondence should be addressed to Wei Lin Li linweilin1977163com

Received 25 April 2013 Accepted 20 June 2013

Academic Editors A Brandi and C Riccardi

Copyright copy 2013 Wei Lin Li et al 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

A simple and efficient synthetic protocol has been developed for the synthesis of 3-substituted-2H-14-benzothiazines by using anovel sulfonic acid functionalized nano-120574-Al

2O3catalyst devoid of corrosive acidic and basic reagentsThe developedmethod has

the advantages of good to excellent yields short reaction times operational simplicity and a recyclable catalyst The catalyst can beprepared by a simple procedure from inexpensive and readily available nano-120574-Al

2O3and has been shown to be recoverable and

reusable up to six cycles without any loss of activity

1 Introduction

14-Benzothiazine derivatives are important biologically andpharmaceutically active heterocyclic compounds They havereceived considerable attention in the field of pharmaceu-tical industry owing to their broad range of biologicalactivities such as antifungal [1 2] immunostimulating [3]antirheumatic [4] antiallergic [5] and antitumor activities[6] 14-Benzothiazines are also active on the cardiovascularsystem and the vasorelaxant antiarrhythmic and antihyper-tensive effects have been reported [7ndash11] 14-Benzothiazinesinduced neurotoxic or neuroprotective effects have beendescribed and a possible role in neurodegenerative diseaseshas been hypothesized [12 13] 14-Benzothiazines provideprivileged scaffolds in lead identificationdrug discovery pro-grams and have provided therapeutically useful compoundsin fields such as anti-rheumatic agents (eg MX-68 [4])histamine H

1-receptor antagonists (eg VUF-K-8788 [5])

aldose reductase inhibitors which are very promising fortreating hyperglycemia (eg SPR-210 [14]) and Ca2+ channelantagonists (eg semotiadil fumarate [11])

There are several methods available for the prepara-tion of 14-benzothiazine derivatives including the ring

expansion of benzothiazoles or benzothiazolines [15 16]basic mediated reactions of o-aminothiophenols with 120596-bromoacetophenones [17] HCl-catalyzed reactions of o-nitrobenzenesulfenyl chlorides with ketones [18] treatmentof aminothioalkenols with p-TsOH or H

3PO4[19] reac-

tion of bis(o-aminophenyl)-disulfide with ketones [20] thecondensation of o-aminothiophenols and 2-bromo-1-aryl-ethanones using KHSO

4[21] and simultaneous reduction

of nitro group and SndashS bond in nitrodisulfides induced bylow-valent titanium reagent [22] Despite the importance ofthese reported protocols many suffer from drawbacks suchas the use of expensive reagents harsh reaction conditionsprolonged reaction times cumbersome product isolationprocedures low yields more stoichiometric amount of cata-lyst Hence to explore a mild efficient and environmentallybenign recyclable synthetic protocol for the 14-benzothiazinederivatives is highly desirable

In recent times the development of environmentallybenign green and easily recyclable catalyst for the produc-tion of fine chemicals has been an area of growing interestIn this context solid acid catalysts play prominent role inorganic synthesis under heterogeneous reaction conditionsVarious solid acid catalysts like zeolite [23] heteropoly

2 The Scientific World Journal

Nano-120574-Al2O3

OHOH

OH Toluene reflux

Nano-120574-Al2O3

SO3H

SO3H

SO3H

SO

OO

OO

O

Scheme 1 Synthesis of sulfonic acid functionalized nano-120574-Al2O3

Br+SH

NH2

CH2 EtOH reflux

Nano-120574-Al2O3

SO3H

SO3H

SO3H

1 2 3

R2 R1

R1R2

S

N

O

OO

O

Scheme 2 Synthesis of 3-substituted-2H-14-benzothiazines using sulfonic acid functionalized nano-120574-Al2O3

acids [24] Amberlyst-15 [25] Nafion-H [26] silica sulfuricacid [27] silica phosphoric acid [28] and silica supportedperchloric acid [29] with lower toxicity high stability andrecyclability have attracted more attention

As a part of our endeavors towards the development ofefficient and environmentally benign synthetic methodolo-gies using economic and eco-friendly heterogeneous catalysts[27 29] we have investigated the synthesis of 3-substituted-2H-14-benzothiazines from o-aminothiophenols and 120596-bromoketones in the presence of a novel sulfonic acidfunctionalized nano-120574-Al

2O3catalyst in EtOH at reflux tem-

perature (Scheme 1)

2 Results and Discussion

Sulfonic acid functionalized nano-120574-Al2O3was easily pre-

pared by the reaction of nano-120574-Al2O3with 13-propanesul-

tone (Scheme 2) and it was characterized by FT-IR X-ray powder diffraction (XRD) thermogravimetric analysis(TGA) and transmission electron microscopy (TEM) Theamount of sulfonic acid loaded on the surface of nano-120574-Al2O3is determined by TG analysis and confirmed by ion-

exchange pH analysisFigure 1 presents the FT-IR spectra of nano-120574-Al

2O3

and sulfonic acid functionalized nano-120574-Al2O3 As shown

in this figure the presence of an extra sulfonic acid groupin the sulfonic acid functionalized nano-120574-Al

2O3increases

the number of vibrational modes and brought completelydifferent FT-IR spectrum The FT-IR spectra of sulfonic acidfunctionalized nano-120574-Al

2O3exhibit two characteristic peaks

at 589 cmminus1 and 758 cmminus1 due to the stretching vibrationsof AlndashO bond in 120574-Al

2O3Moreover two important peaks

at 1043 cmminus1 and 1187 cmminus1 are assigned to SndashO stretchingvibration The broad peak at 3444 cmminus1 belongs to thestretching of OH groups in the SO

3H These results indicate

that the reaction of nano-120574-Al2O3with 13-propanesultone

succeeds in incorporating sulfated groups in nano-120574-Al2O3

XRD measurements of nano-120574-Al2O3and sulfonic acid

functionalized nano-120574-Al2O3exhibit diffraction peaks at

around 195 326 366 395 458 606 and 672 correspond-ing to the (111) (220) (311) (222) (400) (511) and (440) faces

102030405060708090

5001000150020002500300035004000

100

T(

) Nano-n-propylsulfonated 120574-Al2O3

Wave numbers (cmminus1)

Nano-120574-Al2O3

3468

23

3448

71

1639

78

1630

51

1186

53

1043

19

758

1575

766

588

8658

831

Na o 120574 2O3

03000000005

155555555

3448

7

757

66

588

86

NanNaNaNaNNNNNN o-n-propylsulfonated 120574-Al2ll O3

3468

23

1171

1639

78

163

1616161616161

1186

53

1043

19

6

Figure 1 FTIR spectra of nano-120574-Al2O3(up) and sulfonic acid

functionalized nano-120574-Al2O3(down)

(Figure 2)The observed diffraction peaks agree well with thecubic structure of 120574-Al

2O3(JCPDS file number 29-0063) It is

clear that the ordered structure of nano-120574-Al2O3is retained

after introducing the propylsulfonic acid group The averagecrystallite sizes are calculated to be 149 nmusing the Scherrerequation which are in good accordance with TEM results

The stability of the nano-120574-Al2O3and sulfonic acid

functionalized nano-120574-Al2O3is determined by thermogravi-

metric analysis (Figure 3) A significant decrease in theweight percentage of the nano-120574-Al

2O3and sulfonic acid

functionalized nano-120574-Al2O3at about 150∘C is related to

desorption of water molecules from the catalysts surfaceIn the TG curve of sulfonic acid functionalized nano-120574-Al2O3 complete loss of all the covalently attached organic

structures is seen in the temperature range of 230ndash960∘CTheshouldering observed from 328∘C onwards may be due to thedecomposition of alkyl-sulfonic acid groups According tothe TGA the amount of sulfonic acid functionalized nano-120574-Al2O3is evaluated to be 078mmolsdotgminus1 This result is in

agreement with that of ion-exchange pH analysisThe sizes of nano-120574-Al

2O3and sulfonic acid function-

alized nano-120574-Al2O3are further analyzed by TEM and the

results (Figures 4(a) and 4(b)) showed the nanoparticles havenanodimensions ranging from 10 to 20 nm In TEM images

The Scientific World Journal 3

800

600

400

200

0

Nano-120574-Al2O3

10 20 30 40 50 60 70 80 902120579 (deg)

Inte

nsity

(cou

nts)

Sulfonic acid functionalized nano-120574-Al2O3

Figure 2 XRD patterns of nano-120574-Al2O3(up) and sulfonic acid


Nano-120574-Al2O3


110

105

100

95

90

85

80

75100 200 300 400 500 600 700 800 900 1000

TG (

)

T (∘C)

Figure 3 TG analysis of nano-120574-Al2O3(up) and sulfonic acid


the shapes of 120574-Al2O3particles are relatively round and those

of treated n-propylsulfonated 120574-Al2O3are rather rectangular

which is attributed to the presence of sulfonic acid groupscovalently attached to the 120574-Al

2O3surfaces

To achieve suitable conditions for the synthesis of 3-substituted-2H-14-benzothiazines we tested the reaction ofo-aminothiophenol 1 with 2-bromo-1-phenyl-ethanone 2 asa simple model system in EtOH at reflux temperature usingvarious catalysts (Table 1) As could be seen in Table 1 thebest result was obtained with 50mgmmol of sulfonic acidfunctionalized nano-120574-Al

2O3as the catalyst in EtOH at reflux

temperature (entry 3) Using less catalyst resulted in loweryields whereas higher amounts of catalyst did not affectreaction times and yields When this reaction was carried outwithout sulfonic acid functionalized nano-120574-Al

2O3or nano-

120574-Al2O3the yield of the expected product was low In the

presence of p-TsOH sulfamic acid or silica sulfuric acid theproduct was obtained in moderate yield

Accelerating voltage200 kV

Magnification150000 x 20 nm

(a)



(b)

Figure 4 (a) TEM images of nano-120574-Al2O3 (b) TEM images of

sulfonic acid functionalized nano-120574-Al2O3

Table 1 Catalyst optimization for the synthesis of 3-phenyl-2H-14-benzothiazinea

Entry Catalyst Mgmmol Timeh Yieldb

1 mdash mdash 24 42

2 Sulfonic acid functionalizednano-120574-Al2O3

25 4 81


50 3 96


100 3 96


150 3 95

6 Nano-120574-Al2O3 50 24 537 p-TsOH 50 5 798 Sulfamic acid 50 5 819 Silica sulfuric acid 50 6 82aReaction conditions o-aminothiophenol (1mmol) 2-bromo-1-phenyl-ethanone (1mmol) EtOH (10mL) refluxbIsolated yield

To find the optimal solvent for this reaction the modelreaction was carried out at reflux temperature using EtOHH2O CH

2Cl2 THF and CH

3CN as solvents It is shown in

Table 2 that the reaction using EtOH (96) or CH3CN (97)


Table 2 Solvent optimization for the synthesis of 3-phenyl-2H-14-benzothiazinea

Entry Solvent Temperature∘C Timeh Yieldb

1 H2O Reflux 24 122 CH3CN Reflux 3 973 CH2Cl2 Reflux 8 854 THF Reflux 6 885 EtOH 25 10 696 EtOH 40 8 757 EtOH 60 5 898 EtOH Reflux 3 96aReaction conditions o-aminothiophenol (1mmol) 2-bromo-1-phenyl-ethanone (1mmol) sulfonic acid functionalized nano-120574-Al2O3 (50mg)refluxbIsolated yield

as the solvents gave the corresponding product 3-phenyl-2H-14-benzothiazine in high yields (Table 2 entries 8 and 2)From the economic and environmental point of view EtOHwas chosen as the reaction medium for all further reactionsFurthermore the relation between the yields of the modelreaction and temperature was also studied We carried outthe reaction at temperatures ranging from 25∘C to refluxtemperature using EtOH as the reaction medium (Table 2entries 5ndash8) finding that the yields of desired product 3-phenyl-2H-14-benzothiazine were improved as the temper-ature was increased Therefore the best reaction conditionswere obtained in EtOH under refluxed temperature

In order to demonstrate the versatility of the sul-fonic acid functionalized nano-120574-Al

2O3promoted synthe-

sis of 3-substituted-2H-14-benzothiazines a series of 120596-bromoketones were treated with various o-aminothiophenols(Table 3) The reactions proceeded in EtOH at reflux temper-ature within a short time to afford the products The reactionof o-aminothiophenol with various120596-bromoketones resultedin high yields of 3-substituted-2H-14-benzothiazines Thestructures of the products were established from their spec-tral properties (IR 1HNMR and elemental analysis) and alsoby comparison with the available literature data

To demonstrate the recyclability of the catalyst after eachcycle the reactionmixturewas allowed to cool and the catalystwas recovered by simple filtration washed with EtOH anddried in an oven at 100∘C for 30min prior to use Thecatalyst was reused for the same reaction without furtheractivation The reaction proceeded smoothly even after sixcycles without any extension of reaction time or marked lossin yield (Figure 5)

The formation of product may be explained by the reac-tion of 120596-bromoketone 2 with sulfonic acid functionalizednano-120574-Al

2O3which forms an oxonium ion Later it reacts

with o-aminothiophenol and subsequent cyclization result inexpected product (Scheme 3)

3 Conclusion

In conclusion we have developed a novel and reusablesulfonic acid functionalized nano-120574-Al

2O3catalyst for an

Table 3 Preparation of 3-substituted-2H-14-benzothiazinesa

Entry R1 R2 Timeh Product Yieldb

1 H C6H5 3 3a 962 H 4-Me-C6H4 2 3b 973 H 4-MeO-C6H4 2 3c 954 H 4-F-C6H4 4 3d 935 H 4-Cl-C6H4 4 3e 946 H 4-Br-C6H4 4 3f 907 H 4-NO2-C6H4 6 3g 898 H 2-MeO-C6H4 3 3h 909 H 3-NO2-C6H4 6 3i 8810 H 345-(MeO)3-C6H2 6 3j 8611 H 2-Benzofuryl 5 3k 9112 Cl CH3 10 3l 7813 Cl C6H5 3 3m 9314 Cl 4-Me-C6H4 3 3n 9515 Cl 4-MeO-C6H4 3 3o 9316 Cl 4-Cl-C6H4 4 3p 9017 Cl 4-Br-C6H4 4 3q 8718 Cl 2-Benzofuryl 4 3r 8819 CF3 C6H5 4 3s 8620 CF3 4-MeO-C6H4 4 3t 89aReaction conditions o-aminothiophenol (1mmol) 120596-bromoketones(1mmol) sulfonic acid functionalized nano-120574-Al2O3 (50mg) EtOH(10mL) refluxbIsolated yield

0102030405060708090

100

1 2 3 4 5 6

Isolated yield ()

90 899096 8894

Figure 5 Reusability of sulfonic acid functionalized nano-120574-Al2O3

synthesis of 3-phenyl-2H-14-benzothiazine

efficient synthesis of 3-substituted-2H-14-benzothiazinesThe salient features of the present protocol are easy work-up recyclability of the catalyst and good yields The presentprotocol offers a simple inexpensive and versatile approachto the synthesis of 3-substituted-2H-14-benzothiazines

4 Experimental Part

41 Materials and Instrumentation 120574-Alumina powder withparticle size at about 20 nm was purchased from Aladdin(Shanghai China) and was used without further purificationOther reagents and starting materials were purchased fromcommercial resources andwere used as received All productswere characterized by comparison of their spectral and


HS 1

2 3

Nano-120574-Al2O3

R1R2

R1

R2R2

H2NOH+

minusHBr H2OCH2

CH2

BrBr

S

N

O

SO

OOH

Scheme 3 A plausible mechanism for the synthesis of 3-substituted-2H-14-benzothiazines

physical data with those previously reported Progress of thereactions was monitored by TLC

XRD patterns were recorded using a CuK120572 radiationsource on a D8 Advance Bruker powder diffractometerTEM studies were performed using a JEM 2100 transmissionelectron microscope on an accelerating voltage of 150 kVTGA curves are recorded using a DT-40 thermoanalyzerIR spectra were determined on FTS-40 infrared spectrom-eter 1H NMR spectra were determined on Bruker AV-400spectrometer at room temperature using tetramethylsilane(TMS) as an internal standard (CDCl

3solution) coupling

constants (J) were measured in Hz Elemental analysis wasperformed by a Vario-III elemental analyzer Melting pointswere determined on an XT-4 binocular microscope and wereuncorrected

42 Synthesis of Sulfonic Acid Functionalized Nano-120574-Al2O3

Nano-120574-Al2O3(6 g) was suspended in 600mL of 01M

toluene solution of 13-propanesultone and the colloidal solu-tion was refluxed for 48 h The sulfonated nano-120574-Al

2O3was

isolated and purified by repeated washing and centrifugationIt was characterized by FT-IR XRD TGA SEM and TEMThe amount of sulfonic acid loaded on the surface of nano-120574-Al2O3was determined by TG analysis and confirmed by ion-

exchange pH analysis

43 Ion-Exchange pH Analysis To an aqueous solution ofNaCl (1M 25mL) with a primary pH 593 the catalyst(500mg) was added and the resulting mixture was stirred for2 h after which the pH of solution decreased to 181 This isequal to a loading of 078mmol SO

3Hsdotgminus1

44 General Procedure for the Synthesis of 3-Substituted-2H-14-Benzothiazines To a suspension of a 120596-bromoketones(1mmol) and sulfonic acid functionalized nano-120574-Al

2O3

(50mg) in EtOH (10mL) o-aminothiophenol (1mmol) wasadded slowly and the mixture was stirred at reflux tempera-ture The reaction was monitored by TLC After completionthe reaction mixture was filtered The catalyst was washedwith EtOH dried and reused for a consecutive run under thesame reaction conditions Evaporation of the solvent followedby recrystallization from EtOAc gave the desired product ingood to high yields

45 Selected Spectral Data

3-Phenyl-2H-14-benzothiazine (3a) Mp 46ndash48∘C IR (KBr)] 2928 1638 1463 776 cmminus1 1H NMR (400MHz CDCl

3)

746ndash690 (m 9H Ar) 382 (s 2H CH2) anal calcd for

C14H11NS C 7463 H 492 N 622 S 1423 found C 7502

H 499 N 619 S 1420

3-(21015840-Benzofuryl)-2H-14-benzothiazine (3k) Mp 85-86∘CIR (KBr) ] 2933 1669 1472 1246 762 cmminus1 1H NMR(400MHz CDCl

3) 802ndash691 (m 7H Ar) 367 (s 2H CH

2)

anal calcd for C12H9NOS C 6695 H 421 N 651 S 1490

found C 6702 H 418 N 654 S 1497

6-Chloro-3-methyl-2H-14-benzothiazine (3l) Oil IR (KBr)] 2986 2922 1655 1472 1369 766 741 cmminus1 1H NMR(400MHz CDCl

3) 755ndash687 (m 3H Ar) 275 (s 2H CH

2)

209 (s 3H CH3) anal calcd for C

9H8ClNS C 5468 H 408

N 709 S 1622 found C 5472 H 400 N 713 S 1625

6-Chloro-3-phenyl-2H-14-benzothiazine (3m) Mp 64-65∘CIR (KBr) ] 2932 1649 1477 767 738 cmminus1 1H NMR(400MHz CDCl

3) 749ndash682 (m 8H Ar) 382 (s 2H CH

2)

anal calcd for C14H10ClNS C 6473 H 388 N 539 S 1234

found C 6482 H 379 N 542 S 1238

Acknowledgment

This research program was supported by the Foundation ofHenan Educational Committee China (no 12B350005)

References

[1] A Baruffini G Pagani and L Amoretti ldquoDerivatives of 14-benzothiazin-3-onerdquo Il Farmaco vol 22 no 7 pp 528ndash534 1967

[2] F Schiaffella A Guarraci R Fringuelli L Pitzurra F Bistoniand A Vecchiarelli ldquoSynthesis and antifungal activity of newimidazole derivatives of 14-benzothiazinerdquo Medicinal Chem-istry Research vol 9 no 5 pp 291ndash305 1999

[3] LDel Corona G Signorelli A Pinzetta andGCoppi ldquoSynthe-sis and immunostimulating activity of new 14-benzothiazinederivativesrdquo European Journal of Medicinal Chemistry vol 27no 4 pp 419ndash423 1992


[4] H Matsuoka N Ohi M Mihara et al ldquoAntirheumatic agentsnovel methotrexate derivatives bearing a benzoxazine or ben-zothiazine moietyrdquo Journal of Medicinal Chemistry vol 40 no1 pp 105ndash111 1997

[5] T Takizawa J Matsumoto T Tohma et al ldquoVUK-K-8788 aperiphery-selective histamine H1 antagonist with anti-pruriticactivitiesrdquo Japanese Journal of Pharmacology vol 86 no 1 pp55ndash64 2001

[6] S Inoue K Hasegawa K Wakamatsu and S Ito ldquoCompari-son of antimelanoma effects of 4-S-cysteaminylphenol and itshomologuesrdquo Melanoma Research vol 8 no 2 pp 105ndash1121998

[7] F Schiaffella R Fringuelli V Cecchetti A Fravolini P Angeliand G Marucci ldquoEnantiomers of 8-(3-tert-butylamino-2-hydroxypropoxy)-34-dihydro-3-oxo-2H-(14)benzothiazineracemic resolution chiral synthesis and biological activityrdquoFarmaco vol 45 no 12 pp 1299ndash1307 1990

[8] V Cecchetti F Schiaffella O Tabarrini and A Fravolini ldquo(14-benzothiazinyloxy)alkylpiperazine derivatives as potential anti-hypertensive agentsrdquo Bioorganic and Medicinal Chemistry Let-ters vol 10 no 5 pp 465ndash468 2000

[9] V Cecchetti A Fravolini and R Fringuelli ldquoSynthesis and120573-adrenergic blocking activity of oxipropanolamines of 34-dihydro-3-oxo-2H(14)benzothiazinerdquo Il Farmaco vol 42 no1 pp 61ndash75 1987

[10] Y Matsumoto R Tsuzuki A Matsuhisa et al ldquoNovel potas-sium channel openers part 4 transformation of the 14- ben-zoxazine skeleton into 14-benzothiazine 1234-tetrahydro-quinoline 1234-tetrahydroquinoxaline indoline and 15-benzoxazepinerdquo Bioorganic andMedicinal Chemistry vol 8 no2 pp 393ndash404 2000

[11] M Fujita S Ito A Ota et al ldquoSynthesis and Ca2+ antag-onistic activity of 2-[2-[(aminoalkyl)oxy]-5-methoxyphenyl]-34-dihydro-4-methyl-3-oxo-2H-14-benzo-thiazinesrdquo Journalof Medicinal Chemistry vol 33 no 7 pp 1898ndash1905 1990

[12] M Chachin S Shimohama Y U Kunugi and T TaniguchildquoAssessment of protein kinase C mRNA levels in Alzheimerrsquosdisease brainsrdquo Japanese Journal of Pharmacology vol 71 no 2pp 175ndash177 1996

[13] H Li andGDryhurst ldquoIrreversible inhibition ofmitochondrialcomplex I by 7-(2-aminoethyl)-34-dihydro-5-hydroxy-2H-14-benzothiazine-3-carboxylic acid (DHBT-1) a putative nigralendotoxin of relevance to Parkinsonrsquos diseaserdquo Journal of Neu-rochemistry vol 69 no 4 pp 1530ndash1541 1997

[14] T Aotsuka H Hosono T Kurihara Y Nakamura T Mat-sui and F Kobayashi ldquoNovel and potent aldose reductaseinhibitors 4-benzyl- and 4- (benzothiazol-2-ylmethyl)-34-dihydro-3-oxo-2H-14-benzothiazine-2-acetic acid derivativesrdquoChemical and Pharmaceutical Bulletin vol 42 no 6 pp 1264ndash1271 1994

[15] F Chioccara and G Prota ldquoA novel route to 4H-14-benzothia-zines by ring-expansion of 2 3-Dihydro-1 3-benzothiazolesrdquoSynthesis no 12 pp 876ndash878 1977

[16] M Hori T Kataoka H Shimizu and N Ueda ldquoNon-stereospecific ring expansions of benzothiazoline sulfoxidesrdquoTetrahedron Letters vol 22 no 18 pp 1701ndash1704 1981

[17] S Sabatini G W Kaatz G M Rossolini D Brandini and AFravolini ldquoFrom phenothiazine to 3-phenyl-14-benzothiazinederivatives as inhibitors of the Staphylococcus aureus NorAmultidrug efflux pumprdquo Journal of Medicinal Chemistry vol 51no 14 pp 4321ndash4330 2008

[18] I L Finar and A J Montgomery ldquoThe preparation andoxidation of sulphides formed from o-nitrobenzenesulphenylchloride and ketonesrdquo Journal of the Chemical Society pp 367ndash370 1961

[19] A Sauleau M David and J Sauleau ldquoA convenient synthesisof 2H-34-dihydro-14-benzothiazinesrdquo Synthetic Communica-tions vol 28 no 22 pp 4105ndash4121 1998

[20] G Trapani A Latrofa A Reho and C Liso ldquoReaction of2 21015840-dithiodianiline with 2-alkyl-1 3-diketones Synthesis andchemical behaviour of some 2-acyl-2h-1 4-benzothiazinesrdquoJournal of Heterocyclic Chemistry vol 26 no 3 pp 721ndash724l989

[21] B Baghernejad M M Heravi and H A Oskooie ldquoPracticaland efficient synthesis of 3-aryl-2H-benzo[14]thiazine deriva-tives catalyzed by KHSO

4rdquo Synthetic Communications vol 41

no 4 pp 589ndash593 2011[22] Y Zhang W Zhong and X Chen ldquoLow-valent titanium

induced simultaneous reduction of nitro group and S-S bondin nitrodisulfides a facile synthesis of 2H-14-benzothiazinesrdquoChinese Journal of Chemistry vol 19 no 2 pp 189ndash192 2001

[23] A Corma A Martınez and C Martınez ldquoIsobutane2-butenealkylation on ultrastable Y zeolites influence of zeolite unit cellsizerdquo Journal of Catalysis vol 146 no 1 pp 185ndash192 1994

[24] H Firouzabadi and A A Jafari ldquoHeteropoly acids theirsalts and polyoxometalates as heterogenous efficient and eco-friendly catalysts in organic reactions some recent advancesrdquoJournal of the Iranian Chemical Society vol 2 no 2 pp 85ndash1142005

[25] G P Kalena A Jain and A Banerji ldquoAmberlyst 15 catalyzedprenylation of phenols one-step synthesis of benzopyransrdquoMolecules vol 2 no 7 pp 100ndash105 1997

[26] D E Lopez J G Goodwin Jr and D A Bruce ldquoTransesterifi-cation of triacetin withmethanol onNafion acid resinsrdquo Journalof Catalysis vol 245 no 2 pp 381ndash391 2007

[27] L Wu X Yang and F Yan ldquoShort communication silicasulfuric acid a versatile and reusable heterogeneous catalystfor the synthesis of N-ACYL carbamates and oxazolidinonesunder solvent-free conditionsrdquo Bulletin of the Chemical Societyof Ethiopia vol 25 no 1 pp 151ndash155 2011

[28] M A Zolfigol F Shirini K Zamani E Ghofrani and SEbrahimi ldquoSilica phosphoric acidNaNO

2as a novel heteroge-

neous system for the coupling of thiols to their correspondingdisulfidesrdquo Phosphorus Sulfur and Silicon and the RelatedElements vol 179 no 11 pp 2177ndash2182 2004

[29] L Wu Y Wu F Yan and L Fang ldquoHClO4-SiO2-catalyzed

synthesis of 12-aryl-12H-benzo[i][13]dioxolo[45-b]xanthene-611-diones and 10-aryl-67810-tetrahydro-77-dimethyl-9H-[13]dioxolo[45-b]xanthen-9-onesrdquo Monatshefte fur Chemievol 141 no 8 pp 871ndash875 2010

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CatalystsJournal of


Nano-120574-Al2O3

OHOH

OH Toluene reflux

Nano-120574-Al2O3

SO3H

SO3H

SO3H

SO

OO

OO

O

Scheme 1 Synthesis of sulfonic acid functionalized nano-120574-Al2O3

Br+SH

NH2

CH2 EtOH reflux

Nano-120574-Al2O3

SO3H

SO3H

SO3H

1 2 3

R2 R1

R1R2

S

N

O

OO

O

Scheme 2 Synthesis of 3-substituted-2H-14-benzothiazines using sulfonic acid functionalized nano-120574-Al2O3

acids [24] Amberlyst-15 [25] Nafion-H [26] silica sulfuricacid [27] silica phosphoric acid [28] and silica supportedperchloric acid [29] with lower toxicity high stability andrecyclability have attracted more attention

As a part of our endeavors towards the development ofefficient and environmentally benign synthetic methodolo-gies using economic and eco-friendly heterogeneous catalysts[27 29] we have investigated the synthesis of 3-substituted-2H-14-benzothiazines from o-aminothiophenols and 120596-bromoketones in the presence of a novel sulfonic acidfunctionalized nano-120574-Al

2O3catalyst in EtOH at reflux tem-

perature (Scheme 1)

2 Results and Discussion

Sulfonic acid functionalized nano-120574-Al2O3was easily pre-

pared by the reaction of nano-120574-Al2O3with 13-propanesul-

tone (Scheme 2) and it was characterized by FT-IR X-ray powder diffraction (XRD) thermogravimetric analysis(TGA) and transmission electron microscopy (TEM) Theamount of sulfonic acid loaded on the surface of nano-120574-Al2O3is determined by TG analysis and confirmed by ion-

exchange pH analysisFigure 1 presents the FT-IR spectra of nano-120574-Al

2O3

and sulfonic acid functionalized nano-120574-Al2O3 As shown

in this figure the presence of an extra sulfonic acid groupin the sulfonic acid functionalized nano-120574-Al

2O3increases

the number of vibrational modes and brought completelydifferent FT-IR spectrum The FT-IR spectra of sulfonic acidfunctionalized nano-120574-Al

2O3exhibit two characteristic peaks

at 589 cmminus1 and 758 cmminus1 due to the stretching vibrationsof AlndashO bond in 120574-Al

2O3Moreover two important peaks

at 1043 cmminus1 and 1187 cmminus1 are assigned to SndashO stretchingvibration The broad peak at 3444 cmminus1 belongs to thestretching of OH groups in the SO

3H These results indicate

that the reaction of nano-120574-Al2O3with 13-propanesultone

succeeds in incorporating sulfated groups in nano-120574-Al2O3

XRD measurements of nano-120574-Al2O3and sulfonic acid

functionalized nano-120574-Al2O3exhibit diffraction peaks at

around 195 326 366 395 458 606 and 672 correspond-ing to the (111) (220) (311) (222) (400) (511) and (440) faces

102030405060708090

5001000150020002500300035004000

100

T(

) Nano-n-propylsulfonated 120574-Al2O3

Wave numbers (cmminus1)

Nano-120574-Al2O3

3468

23

3448

71

1639

78

1630

51

1186

53

1043

19

758

1575

766

588

8658

831

Na o 120574 2O3

03000000005

155555555

3448

7

757

66

588

86

NanNaNaNaNNNNNN o-n-propylsulfonated 120574-Al2ll O3

3468

23

1171

1639

78

163

1616161616161

1186

53

1043

19

6

Figure 1 FTIR spectra of nano-120574-Al2O3(up) and sulfonic acid


(Figure 2)The observed diffraction peaks agree well with thecubic structure of 120574-Al

2O3(JCPDS file number 29-0063) It is

clear that the ordered structure of nano-120574-Al2O3is retained

after introducing the propylsulfonic acid group The averagecrystallite sizes are calculated to be 149 nmusing the Scherrerequation which are in good accordance with TEM results

The stability of the nano-120574-Al2O3and sulfonic acid

functionalized nano-120574-Al2O3is determined by thermogravi-

metric analysis (Figure 3) A significant decrease in theweight percentage of the nano-120574-Al

2O3and sulfonic acid

functionalized nano-120574-Al2O3at about 150∘C is related to

desorption of water molecules from the catalysts surfaceIn the TG curve of sulfonic acid functionalized nano-120574-Al2O3 complete loss of all the covalently attached organic

structures is seen in the temperature range of 230ndash960∘CTheshouldering observed from 328∘C onwards may be due to thedecomposition of alkyl-sulfonic acid groups According tothe TGA the amount of sulfonic acid functionalized nano-120574-Al2O3is evaluated to be 078mmolsdotgminus1 This result is in

agreement with that of ion-exchange pH analysisThe sizes of nano-120574-Al

2O3and sulfonic acid function-

alized nano-120574-Al2O3are further analyzed by TEM and the

results (Figures 4(a) and 4(b)) showed the nanoparticles havenanodimensions ranging from 10 to 20 nm In TEM images


800

600

400

200

0

Nano-120574-Al2O3

10 20 30 40 50 60 70 80 902120579 (deg)

Inte

nsity

(cou

nts)




Nano-120574-Al2O3


110

105

100

95

90

85

80

75100 200 300 400 500 600 700 800 900 1000

TG (

)

T (∘C)






2O3surfaces




2O3or nano-





(a)



(b)





1 mdash mdash 24 42


25 4 81


50 3 96


100 3 96


150 3 95



2Cl2 THF and CH









2O3promoted synthe-






3 Conclusion


2O3catalyst for an




0102030405060708090

100

1 2 3 4 5 6

Isolated yield ()

90 899096 8894




4 Experimental Part



HS 1

2 3

Nano-120574-Al2O3

R1R2

R1

R2R2

H2NOH+

minusHBr H2OCH2

CH2

BrBr

S

N

O

SO

OOH




3solution) coupling





2O3was




3Hsdotgminus1


2O3




3)


C14H11NS C 7463 H 492 N 622 S 1423 found C 7502

H 499 N 619 S 1420


3) 802ndash691 (m 7H Ar) 367 (s 2H CH

2)


found C 6702 H 418 N 654 S 1497


3) 755ndash687 (m 3H Ar) 275 (s 2H CH

2)


9H8ClNS C 5468 H 408

N 709 S 1622 found C 5472 H 400 N 713 S 1625


3) 749ndash682 (m 8H Ar) 382 (s 2H CH

2)


found C 6482 H 379 N 542 S 1238

Acknowledgment


References













































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


800

600

400

200

0

Nano-120574-Al2O3

10 20 30 40 50 60 70 80 902120579 (deg)

Inte

nsity

(cou

nts)




Nano-120574-Al2O3


110

105

100

95

90

85

80

75100 200 300 400 500 600 700 800 900 1000

TG (

)

T (∘C)






2O3surfaces




2O3or nano-





(a)



(b)





1 mdash mdash 24 42


25 4 81


50 3 96


100 3 96


150 3 95



2Cl2 THF and CH









2O3promoted synthe-






3 Conclusion


2O3catalyst for an




0102030405060708090

100

1 2 3 4 5 6

Isolated yield ()

90 899096 8894




4 Experimental Part



HS 1

2 3

Nano-120574-Al2O3

R1R2

R1

R2R2

H2NOH+

minusHBr H2OCH2

CH2

BrBr

S

N

O

SO

OOH




3solution) coupling





2O3was




3Hsdotgminus1


2O3




3)


C14H11NS C 7463 H 492 N 622 S 1423 found C 7502

H 499 N 619 S 1420


3) 802ndash691 (m 7H Ar) 367 (s 2H CH

2)


found C 6702 H 418 N 654 S 1497


3) 755ndash687 (m 3H Ar) 275 (s 2H CH

2)


9H8ClNS C 5468 H 408

N 709 S 1622 found C 5472 H 400 N 713 S 1625


3) 749ndash682 (m 8H Ar) 382 (s 2H CH

2)


found C 6482 H 379 N 542 S 1238

Acknowledgment


References













































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







2O3promoted synthe-






3 Conclusion


2O3catalyst for an




0102030405060708090

100

1 2 3 4 5 6

Isolated yield ()

90 899096 8894




4 Experimental Part



HS 1

2 3

Nano-120574-Al2O3

R1R2

R1

R2R2

H2NOH+

minusHBr H2OCH2

CH2

BrBr

S

N

O

SO

OOH




3solution) coupling





2O3was




3Hsdotgminus1


2O3




3)


C14H11NS C 7463 H 492 N 622 S 1423 found C 7502

H 499 N 619 S 1420


3) 802ndash691 (m 7H Ar) 367 (s 2H CH

2)


found C 6702 H 418 N 654 S 1497


3) 755ndash687 (m 3H Ar) 275 (s 2H CH

2)


9H8ClNS C 5468 H 408

N 709 S 1622 found C 5472 H 400 N 713 S 1625


3) 749ndash682 (m 8H Ar) 382 (s 2H CH

2)


found C 6482 H 379 N 542 S 1238

Acknowledgment


References













































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


HS 1

2 3

Nano-120574-Al2O3

R1R2

R1

R2R2

H2NOH+

minusHBr H2OCH2

CH2

BrBr

S

N

O

SO

OOH




3solution) coupling





2O3was




3Hsdotgminus1


2O3




3)


C14H11NS C 7463 H 492 N 622 S 1423 found C 7502

H 499 N 619 S 1420


3) 802ndash691 (m 7H Ar) 367 (s 2H CH

2)


found C 6702 H 418 N 654 S 1497


3) 755ndash687 (m 3H Ar) 275 (s 2H CH

2)


9H8ClNS C 5468 H 408

N 709 S 1622 found C 5472 H 400 N 713 S 1625


3) 749ndash682 (m 8H Ar) 382 (s 2H CH

2)


found C 6482 H 379 N 542 S 1238

Acknowledgment


References













































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

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