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ABSTRACT: Protozoic infections caused by genus Leishmania pose an enormous public health threat in developing countries, compounded by the toxicity and resistance to current therapies. Under the aegis of our ongoing program on drug discovery and development on antileishmanial agents from plants, we carried out bioassay guided fractionation on Peganum harmala seeds which resulted in the isolation of 1 as an antileishmanial agent. 2D-NMR spectral data and single crystal X-ray crystallography data indicated 1 as peganine hydrochloride in dihydrated form. The compound 1 exhibited in-vitro activity against both extracellular promastigotes as well as intracellular amastigotes residing within murine macrophages in Leishmania donovani. Furthermore, 1 also exhibited in-vivo activity, 79.6 (+/-8.07)% against established VL in hamsters at a dose of 100mg/kgb.wt.
Bioorganic & medicinal chemistry letters 04/2009; 19(9):2585-6. · 2.65 Impact Factor
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ABSTRACT: A novel series of thermally stable blue light emitting quateraryls with a piperidine donor and a nitrile acceptor was prepared from a ketene- S, S-acetal under mild conditions without using an organometal catalyst. The performance of a blue quateraryl 6e was investigated by fabricating a multilayer OLED with a configuration of ITO/PEDOT:PSS (40 nm)/quateraryl (60 nm)/BCP (6 nm)/Alq(3) (20 nm)/LiF (0.5 nm)/Al (200 nm), which exhibited blue emission with a low turn on voltage of 4 V at a brightness of 0.22 cd/m(2).
Organic Letters 07/2008; 10(12):2553-6. · 5.86 Impact Factor
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ABSTRACT: A series of 2-sulfanyl-6-methyl-1,4-dihydropyrimidines (8-21) were synthesized in good yields by alkylation of 5-methyl-6-phenyl-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid ethyl esters (2-7) with different alkyl or aralkyl halides in the presence of a combination of anhydrous K(2)CO(3) and catalytic amount of tetrabutyl ammonium bromide. The title compounds were evaluated for their antifilarial activity against adult parasites of human lymphatic filarial parasite Brugia malayi (sub-periodic strain) in vitro and in vivo at various concentrations. One of the compounds (18) showed promising antifilarial activity.
European journal of medicinal chemistry 03/2008; 43(12):2717-23. · 3.27 Impact Factor
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ABSTRACT: [reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion.
The Journal of Organic Chemistry 02/2006; 71(2):804-7. · 4.45 Impact Factor
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Synthesis. 01/2006;
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Tetrahedron 01/2006; 62:8731–8739. · 3.03 Impact Factor
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ABSTRACT: A series of 5-[(5-aryl-1H-pyrazol-3-yl)methyl]-1H-tetrazoles 3a-h have been synthesized and evaluated for their in vivo antihyperglycemic activity. Some of the synthesized compounds have shown significant glucose lowering activity in male Sprague-Dawley rats in sucrose loaded model. These compounds were also evaluated for their peroxisome proliferator activated receptor gamma agonistic property, but none of them displayed any significant activity.
Bioorganic & Medicinal Chemistry Letters 05/2005; 15(8):2115-7. · 2.55 Impact Factor
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ABSTRACT: Various 6-aryl-4-substituted-2H-pyran-2-one-3-carbonitriles (1a-d) have been synthesized as precursor for the synthesis of 3,4-dihydro-1H-isothiochroman (2a) and benzocycloalkanes (2b-e). Highly functionalized 9-thiaphenanthrene (3b) and phenanthrene (3a) have also been obtained from the reaction of 1c with thiochroman-4-one and 1-tetralone separately. Similarly 4 has been obtained by the ring transformation of 1d by 4-trifluoromethylacetophenone. Most of the synthesized compounds were evaluated for alpha-glucosidase and protein tyrosine phosphatase inhibitory activities. Some of the compounds, 2a, 3a and b and 4 displayed better alpha-glucosidase inhibitory activity compared to standard drug acarbose.
Bioorganic & Medicinal Chemistry Letters 04/2005; 15(5):1341-4. · 2.55 Impact Factor
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ABSTRACT: In the crystal structure of 1,1'-(1,3-propanediyl)bis(5-ethyl-6-methylthio-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-4-one), C(19)H(24)N(8)O(2)S(2), the pairs of pyrazolo[3,4-d]pyrimidine rings of the molecule stack between the heterocyclic rings, due to intramolecular pi-pi interactions. The substituted ethyl and methyl groups are comparable as far as intramolecular stacking is concerned.
Acta Crystallographica Section C Crystal Structure Communications 12/2001; 57(Pt 11):1324-5. · 0.52 Impact Factor
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ABSTRACT: The title compound, 1-(5,8-dihydro-1,4-dihydroxy-5,8-dioxo-2-naphthyl)-4-methylpent-3-en-1-yl cinnamate, C(25)H(22)O(6), crystallizes in space group P2(1). The phenyl ring of the cinnamate is anti to the carbonyl group of the same moiety [C-C-C-C = -175.6 (2) degrees] and is nearly parallel to the naphthyl ring system. Two six-membered rings formed by intramolecular hydrogen bonds, with O-H...O distances of 2.587 (2) and 2.589 (2) A, occur on either side of the fused ring system, creating a tetracyclic pyrene-shaped system. The phenyl ring forms an intermolecular stack with the benzoquinone ring, as a result of aromatic pi-pi interactions.
Acta Crystallographica Section C Crystal Structure Communications 11/2001; 57(Pt 10):1199-200. · 0.52 Impact Factor
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ABSTRACT: In the crystal structures of 4,6-dimethylthio-1-[3-(4, 6-dimethylthio-2H-pyrazolo[3, 4-d]pyrimidin-2-yl)propyl]-1H-pyrazolo[3,4-d]pyrimidine, C(17)H(20)N(8)S(4), and 1-[4-(4-methoxy-6-methylthio-1H-pyrazolo[3, 4-d]pyrimidin-1-yl)butyl]-5-methyl-6-methylthio-4, 5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-4-one, C(18)H(22)N(8)O(2)S(2), only intermolecular stacking due to aromatic pi-pi interactions between pyrazolo[3,4-d]pyrimidinerings is present.
Acta Crystallographica Section C Crystal Structure Communications 12/2000; 56 Pt 11:1361-3. · 0.52 Impact Factor
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ABSTRACT: The planar furan ring in the title compound (6beta-acetoxyazadirone, C(30)H(38)O(6)) is twisted with respect to the steroid D ring. The crystal structure is stabilized by C-H.O hydrogen bonds and van der Waals interactions.
Acta crystallographica. Section C, Crystal structure communications 07/2000; 56(Pt 6):E253-4. · 0.78 Impact Factor
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ABSTRACT: The crystal structure of [2-(4-bromophenyl)-4-cyano-5-ferrocenylpyrazolo[2,3-a]pyridin-7-yl]acetonitrile, C(26)H(17)N(4)FeBr or [Fe(C(5)H(5))(C(21)H(12)BrN(4))], shows that the pyrazolopyridine ring system (PP), the bromophenyl ring (BP) and the cyclopentadiene ring (Cp) are nearly planar. The PP ring system is twisted out of the plane of the BP and Cp rings by about 20 degrees.
Acta crystallographica. Section C, Crystal structure communications 04/2000; 56(Pt 3):E88-9. · 0.78 Impact Factor
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ABSTRACT: Compound 1 (DL-2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran, CDRI 85/287) a potent anti-estrogen and anti-implantation agent has been successfully resolved into its pure D- and L-enantiomers. Biological studies showed L-enantiomer to be the active form, exhibiting a fivefold higher receptor affinity for the rat uterine cytosolic estrogen receptor, 100% contraceptive efficacy at 1.3 mg/kg dose in single day schedule and 89% inhibition of estradiol induced increase of uterine weight at its contraceptive dose. The absolute stereochemistry determined by X-ray crystallographic analysis showed that the L-enantiomer has 2R configuration at its asymmetric centre.
Bioorganic & Medicinal Chemistry 10/1999; 7(9):2083-90. · 2.92 Impact Factor
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ABSTRACT: Proton NMR analysis of two newly synthesized 'Leonard/trimethylene linker' dissymmetrical compounds 1-(4,6-dimethylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-(5-methyl-6- methylsulfanyl-4-oxo-1,5-dihydropyrazolo[3,4-d]pyrimidin-1-yl)propane (8) and 1-(4-methoxy-6-methylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-(6-met hoxy-5-methyl-4-oxo-1,5-dihydropyrazolo[3,4-d]pyrimidin-1-yl)propane (10) show intramolecularly stacked conformation in solution. X-Ray crystallography of dissymmetrical 'Leonard/trimethylene linker' compound (9) based on pyrazolo[3,4-d]pyrimidine core, for the first time, shows unusual U-motif formed due to intramolecular pi-pi stacking interactions, which is similar to earlier related symmetrical compounds 1 & 2. Supramolecular structures of new compound (8) show additional CH...O, CH...N, CH...S and S...S interactions. (c) 2005 Elsevier B.V. All rights reserved.
Journal of Molecular Structure. 785:106-113.
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ABSTRACT: A concise and convenient synthesis of various partially reduced 6-sec-amino-1,2,3,4,7,8-hexahydro-, 6-sec-amino-1,2,7,8-tetrahydrobenzo[c]phenanthrene-5-carbonitriles, 6-sec-amino-3,4,7,8-tetrahydro-1H-benzo[c]phenanthrene-2-one-5-carbonitr ile cycloalkene ketals, pendant with electron donor and acceptor substituents has been described through base catalyzed ring transformation of 2-oxo-4-sec-amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by cyclohexanone, 2-cyclohexen-1-one, 1,4-cyclohexanedione monocycloalkene ketals. The acid catalyzed deketalation of 6-sec-amino-3,4,7,8-tetrahydro-1H-benzo[c]phenanthrene-2-one-carbonitril e ketals led to yield 6-sec-amino-3,4,7,8-tetrahydro-1H-benzo[c]phenanthrene-3-carbonitrile-2- ones in excellent yield. We also performed the X-ray studies of the molecules 3d and 6a to know the degree of non-planarity. (C) 2009 Published by Elsevier Ltd.
Tetrahedron. 66:1458-1464.
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ABSTRACT: A regioselective approach for the synthesis of substituted naphthofurans and dibenzofurans has been demonstrated through a ring transformation reaction of suitably functionalized 2H-pyran-2-ones by reaction with 6,7-dihydro-5H-benzofuran-4-one and 7-methoxybenzofuran-3-one, respectively, in high yields. The novelty of the procedure lies in the creation of an aromatic ring transformed by 2H-pyran-2-one involving the -COCH2- moiety of a cyclic ketone. (c) 2006 Elsevier Ltd. All rights reserved.
Tetrahedron. 63:1610-1616.
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ABSTRACT: An efficient de novo synthesis of partially reduced naphtho[2,1-h]isoquinolines has been developed through base catalyzed ring transformation of 2-oxo-4-sec-amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by a carbanion, generated in situ from 1-substituted-4-piperidones in DMF and powdered KOH, in excellent yields. The effect of nitrogen insertion in the D ring of partially reduced benzo[c]phenanthrene on conformational changes has also been studied by X-ray diffraction analysis.
Rsc Advances. 2:1299-1302.
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ABSTRACT: An innovative synthesis of aryl tethered 1,2-dihydro-2-oxopyridine-3-carboxylic acids has been developed through nucleophile induced ring transformation of methyl 6-aryl-4-methylsulfanyl-2H-pyran-2-one-3-carboxylates using either cyanamide or arylamidine in excellent yields. Further, the reaction of methyl 6-aryl-4-methylsulfanyl-2H-pyran-2-one-3-carboxylates with formamidine acetate under analogous reaction conditions did not follow the same course of reaction and produced methyl nicotinate, regio selectively, in good yield. Decarboxylation of a 6-aryl-4-methylsulfanyl-1,2-dihydro-2-oxopyridine-3-carboxylic acid has been achieved by heating in PPA. The 4-methylsulfanyl substituent in 3 has also been oxidized to the corresponding methylsulfonyl group with in-chloroperbenzoic acid. (c) 2007 Elsevier Ltd. All rights reserved.
Tetrahedron Letters. 48:4939-4942.
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ABSTRACT: A facile and short synthesis of 2-oxo-4-sec-amino-2,3,5,6-tetrahydrobenzo[f]isoquinoline-1-carbonitriles has been delineated through base catalyzed ring transformation of 5,6-dihydro-2-oxo-4-sec-amino-2H-benzo[h]chromene-3-carbonitrile by cyanoacetamide in excellent yields. (c) 2007 Elsevier Ltd. All rights reserved.
Tetrahedron Letters. 48:7982-7985.
