3-Acetyl-4-hydroxy-6-methyl-2-oxo-2H-pyran (Dehydroacetic acid abbreviated as DHA) has been isolated from natural sources1-2 and is also industrially utilizing a number of synthetic procedures. 3-6 The reactions of DHA and its derivatives have been shown to have a wide utility in organic synthesis. These developments along with the studies on related pyrone derivatives have been reviewed.7

DHA

Since DHA has several reactive sites, the molecule is susceptible to attack by the nucleophilic and electrophilic reagents. A nucleophile can, in principle, attack the carbonyl of the acetyl side chain located at 3-position, the carbon atom terminating the conjugated carbon chain at 6-position, the lactone carbonyl at 2-position and the carbonyl carbon at 4-position of the molecule. On the other hand, an electrophile can attack either at C(3) or C(5). As part of our investigations dealing with the synthesis and mechanistic studies of heterocyclic compounds, we have reported some useful transformations of DHA and its derivatives.8-10. A Literature survey reveals that the reactions of DHA and its derivatives with different reagents can provide a versatile route to the synthesis of a wide variety of heterocyclic compounds

i) Chalcones and cinnamonyl derivatives

Treatment of DHA(1) with aromatic and heteroaromatic aldehydes via microwave assisted Knoevenagel condensation yields 3-cinnamoyl-4-hydroxy-6-methyl-2-oxo-2H-pyrans(2). However, it was found that isolated yields (75-92%) were improved with short span of time (4-10 min). 11

Scheme 1

ii)

1

Reaction of DHA with 5-chloro-3-methyl-1-phenylpyrazole-4-carbaldehyde via claisen-schmidt condensation to afford heterochalcones,which on subsequent treatment with arylhydrazines undergo cyclisation to give hetroaryl-2-pyrazolines.12

iii)Condensation of 3-acetyl-6-methyl-2-oxo-2H-pyran- 4-yl difluoridoborate complex I with heterocyclic aldehydes provided complexes 2, 3 and 5 by heating of the starting compounds in Ac2O or AcOH–H2SO4 mixture. By a reaction of dehydracetic acid (III) with boron trifluoride etherate we obtained its boron complex, 3-acetyl-6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate (IV) (Scheme 1). From condensation of compound IV with aromatic aldehydes Va–Vd difluoridoborates VIa–VId were obtained (Scheme 2). From condensation of compound IV with aromatic aldehydes Va–Vd difluoridoborates VIa–VId were obtained which on treatment with Na2CO3,EtOH,H2O leads to the hydroxyketonesVIIa-VIId. compound IV reacted also with the derivatives of cinnamaldehyde, 4-dimethylaminocinnamaldehyde (VIIIa) and 4-methoxycinnamaldehyde (VIIIb) (Scheme 3).compound 4 reacts with aromatic aldehyde to give IX . 3-Acetyl-6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate (IV) was also brought into condensation with heterocyclic aldehydes (Scheme 4). In this reaction boron complexes XII and XV were obtained. Compound XVIIa was also synthesized by condensation of boron complex IV with two equiv of the corresponding aldehyde. The reaction proceeded simultaneously at both reaction sites. The treatment of boron complexes obtained VIa–VId, IXa, IXb, XII, XV, XVIIa, XVIIb, and XVIId with sodium carbonate in aqueous-alcoholic medium followed by acidification resulted in the formation of the corresponding hydroxyketones VIIa–VIId, Xa, Xb, XIII, XVI, XVIIIa, XVIIIb, and XVIIId. (4-6). 13

2

R=N(CH3)2Br

Table 5

3

Sr no. R Inhibition of IN Catalytic activity IC50(µM) 3-processing Strand transfer Selectivity index

1 N(CH3)2 >100 >100 -2. Br 9 ± 2 3 ± 2 3.2

Scheme 2

R1 = R2 = R4 = H, R3 = N(CH3)2 (a), OCH3 (b); R1 = H, R2 = R3 = R4 = OCH3 (c); R1 = OCH3, R2

= R3 = H, R4 =Br (d).

Scheme 3

4

R = N(CH3)2 (a), OCH3 (b).

Scheme 4

R=C6H6

5

III) PYRANOPYRAZOLES

IV) 5-SUBSTITUTED-4-METHOXY-6-METHYL-2-PYRONES

3-Bromo-4-methoxy-6-methyl-2-pyrone 5 was synthesized in two steps from commercially available triacetic acid lactone in 55% overall yield (Fig. 1). Bromination of commercially available dehydroacetic acid at 0 ˚C, followed by deacetylation with 90% sulphuric acid and then methylation provides 5-bromomethoxy- 6-methyl-2-pyrone 6 starting material in 46% yield.15

Fig 1 Substrates 5 and 6 for Suzuki cross-coupling

Coupling of various arylboronic acids with 5a

6

Compound Pyrone (R)7 CH3(CH2)2

8 CH3(CH2)3

9 CH3(CH2)4

10 CH3(CH2)5

11 C6H5-

Compound Pyrone (R)

12 CH3(CH2)2

13 CH3(CH2)3

14 CH3(CH2)4

15 CH3(CH2)5

16 C6H5-

. Coupling of various arylboronic acids with 5a

Entry Pyrone (R)

7

17 H, 1719 P-CH3,1920 P-Cl,2021 P-CH3O,2122 m-NO,2223 p-CHO,23

. Coupling of various arylboronic acids with 6a

Compound Pyrone(R)24 H25 p-CH3

26 p-Cl27 p-CH3O 28 m-NO2 29 p-CHO

v) 2H-PYRANS AND 2H-PYRIDINES

Arylhydrazines reacted with DHA(1) to give the corresponding 2H‐pyran‐2‐one hydrazones (2), which on treatment with hydrazine hydrate afforded the corresponding 1‐amino‐2H‐pyridin‐2‐ones (3). Reaction of 3 with nitrous acid, aromatic aldehyde and substituted benzenesulfonyl chlorides yielded the corresponding 2H‐pyridine‐2‐one derivatives.16

8

Compound R R1 `or R2

2a C6H5- -2b p‐H2NSO2C₆H₄ -2c p‐ClC₆H -₄ -3a C6H5- -

9

3b p‐H2NSO2C₆H -₄ -3c p‐ClC₆H -₄ -4a C6H5- -5a C6H5- Cyclohexyl5c C6H5- p‐ClC₆H -₄5d p‐ClC₆H -₄ Cyclohexyl6a C6H5- CH3-6b C6H5- CH3(CH3)2CH2

7a C6H5- C6H5-7b C6H5- p‐CH3C₆H₄7c C6H5- p‐CH3OC₆H₄8a C6H5- C6H5-8b C6H5- p‐CH3C₆H₄9a - Cyclohexyl9b - C6H5-9c - p‐ClC₆H -₄

10a - CH3

10b - Cyclohexyl11a - Cyclohexyl11b - C6H5-

11c - p‐ClC₆H -₄12a - Cyclohexyl

vi) Pyrimidines

Reaction of DHA with aromatic aldehydes yields 3-cinnamoyl-4-hydroxy-6-methyl-2-oxo-2H-pyrans (2) which on treatment with S-Benzyl isothiouronium chloride (SBT) in the presence of piperidine as a base give the 6-substituted-4-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-S-benzylthiopyrmidine .17

10

Table 19

Compound Ar3b 3-FC6H4

3i 2-Thienyl3j 4-Pyridyl

VII) AZETIDINONES

Treatment DHA (1) with primary aromatic amines to yield Schiff bases by using microwave system. Schiff bases irradiated with dimethyl formamide in presence of triethyl amine and chloroacetyl chloride to afford azetidinones.18

Table 22.Physical data of compounds (2a-2g) and (3a-3g)

Compounds R1 R2 R3 Yield (%)

2a 1 -OCH3 -H -H 672b 2 -CH3 -H -H 802c 3 -Br -Cl -H 752d 4 -Br -H -H 802e 5 -H -H -H 702f 6 -OH -H -H 692g 7 -H -H -Cl 723a 8 -OCH3 -H -H 763b 9 -CH3 -H -H 743c 10 -Br -Cl -H 723d 11 -Br -H -H 743e 12 -H -H -H 74

11

3f 13 -OH -H -H 723g 14 -H -H -Cl 65

viii) Pyrazoles and Thiazoles

Condensation of 3-(2-bromoacetyl)-4 hydroxy-6-methyl-2H-pyran-2-one (1), thiosemicarbazide (2) and various carbonyl compound give the thiazole and pyrazole derivatives.19

scheme

25

Compound R1 R2 Yield (%)4a 1 CH3 CH3 924b 2 CH3 C6H5 804c 3 CH3 p-tolyl 804d 4 CH3 p-anisyl 824e 5 CH3 Et 804f 6 Cyclohexylidine cyclohexylidine 814g 7 H Ph 77

12

4h 8 H O-hydroxyphenyl 874i 9 H p-tolyl 804j 10 H p-anisyl 78

ix) Isoxazolyl thiazolyl pyrazoles

The reaction of DHA(1) with thiosemicarbazide which is converted into the hydrazones.the rearrangement in ethanol-acetic acid mixture to afford the key intermediate 1-(5-hydroxy-3-methyl-1-substituted pyrazol-4-yl)-1,3-butanediones which on treatment with hydroxylamine hydrochloride to yield 1-(4-phenyl/4-substitutedphenyl)thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-H-pyrazol-5-ol. 20

Table 29

compounds R Yield (%)

3a C6H5 763b P-CH3-C6H5 713c P-OCH3-

C6H5

73

3d P-Cl-C6H5 674a C6H5 57

13

4b P-CH3-C6H5 59

x) Pyrazolo[4,3-c]pyridine-4-ones

All 3,6-dimethyl-l-phenyl-l~-pyrazolo[4,3-c]pyridine-4- one derivatives (5) were prepared from dehydroacetic acid (1) as the starting material. The reaction of 1 with an appropriatephenylhydrazine derivative (2) in ethanol afforded hydrazone derivatives (3), which were converted to fused compounds (4) by dehydrating in the presence of p-toluenesulfonic acid. Theammonolysis of 4 with saturated ethanolic ammonia afforded lactam derivatives (5) in fair yield (Scheme I). Alkoxy (71, acyloxy (81, and methylsulfonyloxy (9) derivatives were preparedby the methods shown in Scheme II. Briefly, demethylation of methoxy derivative (5a) with pyridine hydrochloride afforded the hydroxy derivative (6). Alkylation of 6 with an appropriate alkyl halide in the presence of anhydrous potassium carbonate, acylation of 6 with an appropriate acid anhydride in pyridine, and methylsulfonylation of 6 with methylsulfonyl chloride in the presence of tiethylamine afforded 7, 8, and 9, respectively (Scheme 11). Thiation of 4 with phosphorus pentasulfide afforded thiolactone derivatives (lo), which were converted in the same manner as described for 5 to the thiolactam derivative (11). The acetoxy derivative (13) was obtained by demethylation of llb and subsequent acetylation of 12 in the same manner as described for 8 (Scheme 111).21

14

Table31

Compound

R Yield (%)

8a 1 CH3 7811a 2 H 7512 3 - 68

15

xi) Pyrazolo-oxazin-2-ones

DHA reacts with phenylhydrazine to give the 1,3-dicarbonyl compound 2 . Reaction of derivatives 2 with aliphatic and aromatic primary amines lead to pyrazolyl-enaminones 3 which react with thiophosgene in presence of triethylamine to give N-substituted substituted pyrazolo-oxazin-2-thione compounds.22

Scheme 24

Table33

Compounds R Yield (%)4a 1 CH3CH2 744b 2 CH3CH2CH2 714c 3 CH2C6H4 764d 4 C6H6 824e 5 4-CH3-C6H4 864f 6 4-OCH3-C6H4 804g 7 4-Br-C6H4 72

xii) Pyrazolo-oxazinonesScheme 1 outlines our general strategy developed to obtain the pyrazolo-oxazinones 4a–k. This procedure starts with the reaction of the commercially available dehydroacetic acid 1 with phenylhydrazine to give in two steps the 1,3-dicarbonyl compound 2 according to the literature procedure.34 Exposure of 2 to aliphatic and aromatic primary amines led to pyrazolo-enaminones 3a–k using the method reported in the reference.35 Ring closure of compounds 3a–k

16

with triphosgene in dichloromethane in the presence of triethylamine provided the target compounds 4a–k in 70–85% yields.23

a. R= C2H5 d. R= 2-thienylb. R= n-C4H9 e. R= C6H5-CH2

c. R= isobutyl f. R= C6H5

g. R= 4-CH3C6H4 j. R= 4-ClC6H4

h. R= 4-CH3OC6H4 K. R= 4-BrC6H4

i. R= 4-CH3O2CC6H4

Scheme 25.

Compound R Yield (%)

4a C2H5 784b n-C4H9 764c (CH3)2CHCH2 744d 2-thienyl 714e C6H5-CH2 724f C6H5 824g 4-CH3C6H4 854h 4-CH3OC6H4 844i 4CH3O2CC6H4 704j 4-ClC6H4 724k 4-BrC6H4 72

17

xii) Pyrano[2,3-c] pyrazol-4-ones

Scheme 26

Table 37

Tale VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV1TTTTTGGLKK4646464646AJJT binding activityComp R R1 R2 Yield

(%)1a H CH3 H 251b NO2 CH3 H 201c NH2 CH3 H 302a H - - 202b NO2 - - 25

XIV) PYRIDAZINE

3-Acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (dehydroacetic acid) (1) prepared from ethylacetoacetate, on refluxing with Conc. H2SO4 gives 4-hydroxy-6-methyl-2- pyrone . This on coupling with diazonium chloride, prepared by conventional diazotization technique from an amine of the formula R-NH2 (where R is phenyl or substituted phenyl) gave hydrazone , which on treatment with an aqueous acid yields pyridazine-3-carboxylic acid.25

18

Scheme 16

Table26

S NO Compounds R Yield(%)1 5a 4-F 682 5b 4-CN 353 5c 4-CF3 404 5d 3-F 765 5e 2,4-Difluoro 566 5f 3,5-Difluoro 457 5g 3,4-Difluoro 428 5h 4-COOH 409 5i 4-CONH2 45

Metal complexesi)The ligand have been synthesized by the condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H) pyran-2,4(3H)-dione or DHA), o-phenylene diamine and fluoro benzaldehyde.(26)

19

Scheme 27

Figure . Proposed structure of the metal complexes, where M= Cu(II), Ni(II), Co(II), Mn(II) and Fe(III).

ii)The new ruthenium(II) carbonyl complexes of dehydroacetic acid thiosemicarbazone of the type [Ru(dhatsc)(CO)(B)(EPh3)] (Scheme 1) have been obtained from the reaction of [RuHCl(CO)(-B)(EPh3)2] (where E = P, B = PPh3, py, pip (or) mor; E = As, B = AsPh3) with tridentate Schiff base H2dhatsc in dry benzene in 1:1 molar ratio.(27)

20

Scheme 28. Structure of ruthenium(II) carbonyl complexes of dhatsc

Table 39Analytical data of ruthenium(II) carbonyl complexes of DHATSC

S.no Complexes1 [Ru(dhatsc)(CO)(PPh3)2]2 [Ru(dhatsc)(CO)(Py)(PPh3)2]3 [Ru(dhatsc)(CO)(PiP)(PPh3)2]4 [Ru(dhatsc)(CO)(Mor)(PPh3)2]5 [Ru(dhatsc)(CO)(AsPh3)2]

iii)The solid complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with asymmetrical tetradentate Schiff bases derived from o-phenylenediamine (H2L1)/4-methyl o-phenylenediamine (H2L2), 3-Acetyl-6-methyl-pyran-2,4-dione (Dehydroacetic acid) and 2-hydroxy-1-naphthaldehyde have been synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, uv-visible, i.r, 1H-nmr. spectra, X-ray diffraction, thermal analysis, and screened for antimicrobial activity.(28)

21

R = H / CH3

Figure 1. Structure of ligand

Figure 2(a)

Fig. 2(b)k

22

R = H / CH3

Fig.2. The proposed structure of the complexes.(a)When M = Cu(II) and Ni(II); (b) When M = Co(II), Mn(II) and Fe(III)

iv)

The solid complexes of MnII, FeIII, CoII, NiII and CuII with 3-(3-furan-2yl-acryloyl)-6-methyl-pyran-2,4-dione(L1) and 3-(3-thiophene-2yl-acryloyl)-6-methyl-pyran-2,4-dione (L2) have been synthesized.(29)

Fig. 1. Structure of ligand. Legends: R=O or S.

Fig. 2. The proposed structure of the complexes. Legends: R=O or S. X = H2O; When M = MnII, CoII, NiII and CuII, X = Cl; When M = FeIII.

The solid complexes of MnII, FeIII, CoII, NiII and CuII with 3-(3-furan-2yl-acryloyl)-6-methyl-pyran-2,4-dione(L1) and 3-(3-thiophene-2yl-acryloyl)-6-methyl-pyran-2,4-dione (L2) have been synthesized.(30)

23

Fig. 1. Structure of ligand. Legends: R=O or S.

Fig. 2. The proposed structure of the complexes. Legends: R=O or S. X = H2O; When M = MnII, CoII, NiII and CuII, X = Cl; When M = FeIII

1 Rivera C.; Pineyro,E.; Giral,F. Dehydroacetic acid in anthers of Solandra nitida (Solanaceae)

Experientia, 1976, (32), 1490.

2. Ohno,H.; Saheki, T.; Awaya,J.; Nakagawa,A.; Omura,S. J. Antibiot., 1978, 31(11), 1116-1123

3. F. Arndt, and P. Nachtwey, Chem Ber., 1954, 57, 1489; (Chem. Abstr., 1925, 19, 286).

24

4. Steele, A. B.; Boese, and M. F. Dull. Heterogeneous Catalysis and Fine Chemicals II. J. Org. Chem., 1949, 14, 460.

5. Kaushol,R. Heterogeneous Catalysis and Fine Chemicals II J. Indian Chem. Soc., 1946, 23, 16.

6. Pechmann,V.B. Heterocyclic Compounds.1891, (24), 194

7. M. M. Manas, and R. Pleixats, ‘Advances in Heterocyclic Chemistry’ J. Am9. Chem. Soc., 1992, 53, 1.

8. Singh,S.P.; Grover,M.; Tarar,L.S.; Elguero,J.; Martinez,A. A 1H and 13c Nmr study of the structure and tautomerism of 4-pyrazolylpyrazolinones . J. Heterocycl. Chem., 1990, 27, 865.

9. Singh,S.P.; Kumar,D,; Batra,H.; Naithani,R.; Rozas,J.; Elguero,J. The reaction between hydrazines and -dicarbonyl compounds: proposal for a mechanism J. Chem., 2000, 78, 1109.

10. O. Prakash, A. Kumar, Anil Sadana, and S. P. Singh, Synth. Commun. 2002, 32, 2663

11 Prasad,Y.R.; Rajasekhar,K.K.; Shankarananth,V.; B, kumar, G.S.S.P; Teja,S.P.S.; Reddy,B.R. In silico Biological Activity Evaluation of some 3-substituted-4-hydroxy-6-methyl-2HPyran- 2-ones. Journal of Pharmacy Research, 2010, 3(10), 2470-2472.

12 Siddiqui,Z.N.; Shagufta, P.; Mohammed, M.T. N. Synthesis and antibacterial evaluation of novel heterocycles from 5-chloro-3- methyl-1-phenylpyrazole-4-carbaldehyde. Indian Journal of chemistry, 2011, 50(B), 910-917.

13Tambov,K.V.;Voevodina,I.V.;Manaev,A.V.;IvanenkovY.A.;Neamati,N.;Travena,V.F.Structures and biological activity of cinnamoyl derivatives of coumarins and dehydroacetic acid and their boron difluoride complexes. Russian Chemical Bulletin,2012 ,61,78-90.

14 Kumar, A., Lohan,L., Aneja,D.K., Kumar Gupta,G., Kaushik,D., Om,P.Design. synthesis, computational and biological evaluation of some new hydrazino derivatives of DHA and pyranopyrazoles.European Journal of Medicinal Chemistry,2012,(50), 81-89.

15 Faidallah, H.M.; Khan,K.A.; Mohammad A,A. Synthesis and characterization of a novel series of benzenesulfonylurea and thiourea derivatives of 2H‐pyran and 2H‐pyridine‐2‐ones as antibacterial, antimycobacterial and antifungal agents. European Journal of Chemistry, 2011, 2 (2), 243‐250.

16 Kaur,N.; Aggarwal,A.K.; Sharma,N.; Choudhary,B.Synthesis and In-vitro Antimicrobial Activity of Pyrimidine Derivatives. International Journal of Pharmaceutical Sciences and Drug Research, 2012, 4(3), 199-204.

25

17 Pulate,C.P.; Gurubasavrajswamy, P. M.; Antre,R.V.; Goli,D. Discovery Microwave-Assisted Synthesis and Antimicrobial Activity of Novel Azetidinones from Dehydroacetic Acid. International Journal of Drug Design and Discovery.2011, 2, 483-487.

18 Penta,S.; Vedula,R.R. A facile one-pot synthesis of thiazoles and thiazolyl-pyrazole derivatives via multicomponent approach. Org. Commun, 2012, 5(3), 143-149.

19 Nagawade,R.R.; Khanna,V.V.; Bhagwat,S.S.; Shinde,D.B. Synthesis of new series of 1-Aryl-1,4-dihydro-4-oxo-6-methyl pyridazine-3-carboxylic acid as potential antibacterial agents. European Journal of Medicinal Chemistry. 2005, 40, 1325–1330.

20 Mor,S.; Mohil,R.;Kumar,D.;Ahuja,M.Synthesis and antimicrobial activities of some isoxazolyl thiazolyl pyrazoles.med chem. Res,2012,21,3541-3548.

21 Bennamane,N.; Kolli,B.N.; Geronikaki,A.A.; Eleftheriou,P.Th.; Kaoua,R.; Boubekeur,K.; Hoffman,P.; Chaudhary,S.S.; Saxena,A.K. N-Substituted [phenyl-pyrazolo]-oxazin-2-thiones as COX-LOX inhibitors: influence of the replacement of the oxo-group with thioxo group on the COX inhibition activity of N-substituted pyrazolo-oxazin-2-ones.ARKIVOC, 2011, 69-82.

22 Benaamane,N.; Kolli,B.N.; Bentarzi,Y.; Hammal,L.; Geronikaki,A.; Eleftheriou,P.; Lagunin,A.Synthesis and in silico biological activity evaluation of new N-substituted pyrazolo-oxazin-2-one systems. Bioorganic & Medicinal Chemistry.2008, 16, 3059–3066.

23 Colotta,V.; Catarzi,D.; Varano,F.; Melani,F.; Filacchioni,G.; Cecchi,L.; Trincavelli,L.; Martini,C.; Lucacchini,A. Synthesis and A1 and A2A Adenosine binding activity of some pyrano [2,3-c]pyrazol-4-ones. Farmaco,1998,53, 189-196.

24 Jadhav,S.M.; Shelke,V.A.; Shankarwar,S.G.; Munde,A.S.; Chondhekar,T.K. Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand. Journal of Saudi Chemical Society, 2011

25Kannan,S.;Sivagamasundari,M.;R,R.;Liu,Y. Ruthenium(II) carbonyl complexes of dehydroacetic acid thiosemicarbazone. Synthesis, structure, light emission and biological activity. Journal of Organometallic Chemistry, 2008,693, 2251–2257.

26Munde,A.S.; Shelke,V.A.; Jadhav,S.M.; Kirdant,A.S.; Vaidya,S.R.; Shankarwar,S.G.; Chondhekar,T.K.. Synthesis, Characterization and Antimicrobial Activities of some Transition Metal Complexes of Biologically Active Asymmetrical Tetradentate Ligands. Advances in Applied Science Research. 2012, 3 (1), 175-182.

26

27Patange,V.N.;Arbad,B.R.;Mane,V.G.;Salunke,S.D.Synthesis,physico-chemicaland antimicrobial screening studies of some transition metal complexes with O:O donor ligands. Transition Metal Chemistry. 2007, 32,944–949.

28Chitrapriya,N.;Kamatchi,T.S.;Zeller,M.;Lee,H.;Natarajan,k.Synthesis,spectroscopic,crystal structure and DNA binding of Ru(II) complexes with 2-hydroxy-benzoic acid[1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-ethylidene]-hydrazide.Spectrochimica Acta,2011,81,128-134

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