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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
2.
Roland K. Robins Ganapathi R. Revankar Darrell E. O'Brien Robert H. Springer Thomas Novinson Anthony Albert Keitaro Senga Jon P. Miller David G. Streeter 《Journal of heterocyclic chemistry》1985,22(3):601-634
A number of new hypoxanthine analogs have been prepared as substrate inhibitors of xanthine oxidase. Most noteworthy inhibitory new hypoxanthine analogs are 3-(m-tolyl)pyrazolo[1,5-a]pyrimidin-7-one ( 47 ), ID50 0.06 μM and 3-phenylpyrazolo[1,5-a]pyrimidin-7-one ( 46 ), ID50 0.40 μM. 5-(p-Chlorophenyl)pyrazolo[1,5-a]pyrimidin-7-one ( 63 ) and the corresponding 5-nitrophenyl derivative 64 exhibited an ID50 of 0.21 and 0.23 μM, respectively. 7-Phenylpyrazolo[1,5-a]-s-triazin-4-one ( 40 ) is shown to exhibit an ID50 of 0.047 μM. The structure-activity relationships of these new phenyl substituted hypoxanthine analogs are discussed and compared with the xanthine analogs 3-m-tolyl- and 3-phenyl-7-hydroxypyrazolo[1,5-a]pyrimidin-5-ones ( 90 ) and ( 91 ), previously reported from our laboratory to have ID50 of 0.025 and 0.038 μM, respectively. The presence of the phenyl and substitutedphenyl groups contribute directly to the substrate binding of these potent inhibitors. This work presents an updated study of structure-activity relationships and binding to xanthine oxidase. In view of the recent elucidation of the pterin cofactor and the proposed binding of this factor to the molybdenum ion in xanthine oxidase, a detailed mechanism of xanthine oxidase oxidation of hypoxanthine and xanthine is proposed. Three types of substrate binding are viewed for xanthine oxidase. The binding of xanthine to xanthine oxidase is termed Type I binding. The binding of hypoxanthine is termed Type II binding and the specific binding of alloxanthine is assigned as Type III binding. These three types of substrate binding are analyzed relative to the most potent compounds known to inhibit xanthine oxidase and these inhibitors have been classified as to the type of inhibitor binding most likely to be associated with specific enzyme inhibition. The structural requirements for each type of binding can be clearly seen to correlate with the inhibitory activity observed. The chemical syntheses of the new 3-phenyl- and 3-substituted phenylpyrazolo[1,5-a]pyrimidines with various substituents are reported. The syntheses of various 8-phenyl-2-substituted pyrazolo-[1,5-a]-s-triazines, certain s-triazolo[1,5-a]-s-triazines and s-triazolo[1,5-a]pyrimidine derivatives prepared in connection with the present study are also described. 相似文献
3.
T. Sudhakar Rao Ganapathi R. Revankar Ravi S. Vinayak Roland K. Robins 《Journal of heterocyclic chemistry》1991,28(7):1779-1788
Several disubstituted pyrazolo[3,4-d]pyrimidine, pyrazolo[1,5-a]pyrimidine and thiazolo[4,5-d]pyrimidine ribonucleosides have been prepared as congeners of uridine and cytidine. Glycosylation of the trimethylsilyl (TMS) derivative of pyrazolo[3,4-d]pyrimidine-4,6(1H,5H,7H)-dione ( 4 ) with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose ( 5 ) in the presence of TMS triflate afforded 7-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)pyrazolo-[3,4-d]pyrimidine-4,6(1H,5H)-dione ( 6 ). Debenzoylation of 6 gave the uridine analog 7-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-4,6(1H,5H)-dione ( 3 ), identical with 7-ribofuranosyloxoallopurinol reported earlier. Thiation of 6 gave 7 , which on debenzoylation afforded 7-β-D-ribofuranosyl-6-oxopyrazolo[3,4-d]pyrimidine-4(1H,5H)-thione ( 8 ). Ammonolysis of 7 at elevated temperature gave a low yield of the cytidine analog 4-amino-7-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-6(1H)-one ( 11 ). Chlorination of 6 , followed by ammonolysis, furnished an alternate route to 11 . A similar glycosylation of TMS-4 with 2,3,5-tri-O-benzyl-α-D-arabinofuranosyl chloride ( 12 ) gave mainly the N7-glycosylated product 13 , which on debenzylation provided 7-β-D-arabinofuranosylpyrazolo[3,4-d]pyrimidine-4,6(1H,5H)-dione ( 14 ). 4-Amino-7-β-D-arabinofuranosyl-pyrazolo[3,4-d]pyrimidin-6(1H)-one ( 19 ) was prepared from 13 via the C4-pyridinium chloride intermediate 17 . Condensation of the TMS derivatives of 7-hydroxy- ( 20 ) or 7-aminopyrazolo[1,5-a]pyrimidin-5(4H)-one ( 23 ) with 5 in the presence of TMS triflate gave the corresponding blocked nucleosides 21 and 24 , respectively, which on deprotection afforded 7-hydroxy- 22 and 7-amino-4-β-D-ribofuranosylpyrazolo[1,5-a]pyrimidin-5-one ( 25 ), respectively. Similarly, starting either from 2-chloro ( 26 ) or 2-aminothiazolo[4,5-d]pyrimidine-5,7-(4H,6H)-dione ( 29 ), 2-amino-4-β-D-ribofuranosylthiazolo[4,5-d]pyrimidine-5,7(6H)-dione ( 28 ) has been prepared. The structure of 25 was confirmed by single crystal X-ray diffraction studies. 相似文献
4.
The synthesis of 3-cyano-2-(β-D-ribofuranosyl)indazole (4) has been accomplished by a condensation of N-trimethylsilyl-3-cyanoindazole (1) with 2,3,5-tri-O-aeetyl-D-ribofuranosyl bromide (2) followed by subsequent deacetylation. The reactivity of the 3-cyano group was demonstrated by the conversion of 4 to 2-(β-D-ribofuranosyl)indazole-3-carboxamide (5) and 2-(β-D-ribofuranosyl)indazole-3-thiocarboxamide (6). The site of ribosylation and the assignment of anomeric configuration for 4 is discussed. The magnetic anisotropy effect of the exocyclic group at C3 on the anomeric proton as determined by pmr spectroscopy is discussed. 相似文献
5.
Ric H. B. Meyer Ganapathi R. Revankar P. Dan Cook Kenneth W. Ehler Martin P. Schweizer Roland K. Robins 《Journal of heterocyclic chemistry》1980,17(1):159-169
The total synthesis of 6-amino-1,2,3-triazolo[4,5-c]pyridin-4(5H)one (8-aza-3-deazaguanine, 3 ) and 6-amino-1-(β-D-ribofuranosyl)-1,2,3-triazolo[4,5-c]pyridin-4(5H)one (8-aza-3-deazaguano-sine, 22 ) has been described for the first time by a novel base-catalyzed ring closure of 4(5)-cyanomethyl-1,2,3-triazole-5(4)carboxamide (14) and methyl 5-cyanomethyl-1-(2,3,5-tri-O-ben-zoyl-β-D-ribofuranosyl)-1,2,3-triazole-4-carboxylate (17) , respectively. Under the catalysis of DBU, 2,4-dinitrophenylhydrazone of dimethyl 1,3-acetonedicarboxylate (7) was converted to methyl 5-methoxycarbonylmethyl-1-(2,4-dinitroanilino)-1,2,3-triazole-4-carboxylate (12) via dimethyl 2-diazo-3-iminoglutarate (8) . Catalytic reduction of 12 gave methyl 4(5)methoxycar-bonylmethyl-1,2,3-triazole-5(4)carboxylate (11) from which methyl 4(5)carbamoylmethyl-1,2,3-triazole-5(4)carboxylate (10) was obtained by ammonolysis. Dehydration of 10 provided methyl 4(5)cyanomethyl-1,2,3-triazole-5(4)carboxylate (13) which on amination gave 14 . The 1,2,3-triazole nucleosides 17, 18 and 19 were obtained from the stannic chloride-catalyzed condensation of the trimethylsilyl 13 and a fully acylated β-D-ribofuranose. The yield and ratio of the ribofuranosyl derivatives of 13 markedly depends on the ratio of stannic chloride used. The structures of the nucleosides 22 and 23 were established by a combination of NOE, 1H-nmr and 13C-nmr spectroscopy. 相似文献
6.
The synthesis of 5,6-dichloro-1-(β-D -ribofuranosyl)benzotriazole ( 4a ), 5,6-dimethyl-1-(β-D -ribofuranosyl)benzotriazole ( 4b ) and 1-(β-D -ribofuranosyl)benzotriazole ( 4c ) in good yield has been accomplished by the condensation of the appropriate 1-trimethylsilylbenzotriazole ( 1a, 1b , and 1c ) with 2,3,5-tri-O-acetyl-D -ribofuranosyl bromide (2) followed by subsequent deacetylation of the reaction products. The assignment of anomeric configuration and site of glycosidation for all nucleosides reported is discussed. 相似文献
7.
A solution for the flow problem of an elastico-viscous fluid (Walters liquid B) due to an oscillating infinite porous plate with constant suction has been obtained. It has been observed that the magnitude of velocity decreases with increase in suction velocity. The shearing stress increases with increase in suction.We thank the referee for his useful suggestions. 相似文献
8.
Satish M. Annigeri M. P. Sathisha Vidyanand K. Revankar 《Transition Metal Chemistry》2007,32(1):81-87
Binuclear cobalt(II), nickel(II), copper(II) and zinc(II) complexes of general composition [M2L1-2(μ-Cl)Cl2] · nH2O with the Schiff-base ligands (where L1H and L2H are the potential pentadentate ligands derived by condensing 2,6-diformyl-4-methylphenol with 4-amino-3-antipyrine and 2-hydroxy-3-hydrazinoquinoxiline,
respectively) have been synthesized and characterized. Analytical and spectral studies support the above formulation. 1H-NMR and IR spectra of the complexes suggest they have an endogenous phenoxide bridge, with chloride as the exogenous bridge
atom. The electronic spectra of all the complexes are well characterized by broad d–d and a high intensity charge-transfer
transitions. The complexes are chloro-bridged as evidenced by two intense far-IR bands centered around 270–280 cm−1. Magnetic susceptibility measurements show that complexes are antiferromagnetic in nature. The compounds show significant
growth inhibitory activity against fungi Aspergillus niger and Candida albicans and moderate activity against bacteria Bacillus cirroflagellosus and Pseudomonas auresenosa. 相似文献
9.
Dhoolesh Gangaram Kokare Krishna Naik Anupama Nevrekar Avinash Kotian Vinayak Kamat Vidyanand K. Revankar 《应用有机金属化学》2016,30(4):181-187
Mononuclear divalent complexes of Co, Ni, Cu and Zn derived from a benzofuran‐based novel hydrazone tridentate ligand were synthesized and characterized using various spectroscopic methods. Elemental analysis reveals that the metal‐to‐ligand ratio is 1:2 which is supported by mass spectrometry results. Conductivity measurements suggest that all the complexes are non‐electrolytic in nature. The ligand and complexes were evaluated for their antimicrobial potency. Bioassay of all hydrazone chelates shows enhanced activity as compared to that of the ligand. The complex with cobalt ion as the metal centre shows better activity against fungi than the standard. Also, ligand and complexes were screened for antituberculosis activity; some analogues (Ni, Cu, Zn) are eight times more active than the standard. Both ligand and complexes show moderate ability to cleave calf thymus DNA. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
Miss K. H. Sinnur G. R. Revankar S. Siddappa 《Monatshefte für Chemie / Chemical Monthly》1966,97(2):417-422
Zusammenfassung Eine Reihe von Hydroxybenzylbenzimidazolen wurde durch Kondensation verschiedener aromatischer o-Diamine mit Brommandelsäuren unter Verwendung von 6n-HCl als Kondensationsmittel hergestellt. Für die Substituenten in der Benzolhälfte wurden die Stellungen 4(7)-, 5(6)-, 5,6- oder 4,6(5,7)- ge-wählt; der Phenylrest der Hydroxybenzylhälfte trägt ein Bromatom in der o- oder p-Stellung. Die Darstellung der o-Brom-mandelsäure wird beschrieben.
A series of hydroxybenzylbenzimidazoles has been synthesized by condensing various aromatic o-diamines with bromomandelic acids using 6 N hydrochloric acid as condensing agent. o-Phenylene diamines to yield benzimidazoles substituted at positions 4(7)-, 5(6)- or 4,6(5,7)- were selected; the phenyl group of the hydroxybenzyl moiety carries a bromo substituent in the o- or p-position. The preparation of o-bromomandelic acid is described in some detail.相似文献