SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF NOVEL PYRAZOLO[3,4-b]PYRIDINES AND THEIR SPIRO-HETEROCYCLIC DERIVATIVES

The present work describes the synthesis of a novel series of heterocyclic moieties derived from 5-acetylpyrazolo[3,4-b]pyridine (1). The formation of chalcones (2a-d) was utilized to synthesize pyrazoline, isoxazoline and pyrimidine derivatives (3-10). Thiosemicarbazone and semicarbazone (11, 17) were utilized to synthesize other new triazolethiones, thiadiazole and selenadiazole derivatives (11-19). Some new spiro derivatives (22-25) were synthesized by the reaction of chalcone (21) of 1 and isatine with hydrazines, hydroxyl amines and thiourea. Also, The reaction of 1 with cyanoacetyl hydrazine gave the hydrazide-hydrazone derivative 26, which was allowed to react with aromatic aldehydes and α-cyanocinnamonitrile to afford coumarine and substituted pyridine derivatives (28, 29). The structures of all the new compounds have been established on the basis of their analytical and spectral data. Twenty two of the synthesized compounds were also evaluated for their antibacterial and antifungal activity against various strains of bacteria and fungi and most are found to possess promising antimicrobial activity when compared with Chloramphenicol and Clotrimazol

Synthesis and reactions of 9,10-dihydro-9,10-ethanoanthracene-11,12-diacid hydrazides

1009-101

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF NOVEL PYRAZOLO[3,4-b]PYRIDINES AND THEIR SPIRO-HETEROCYCLIC DERIVATIVES

The present work describes the synthesis of a novel series of heterocyclic moieties derived from 5-acetylpyrazolo[3,4-b]pyridine (1). The formation of chalcones (2a-d) was utilized to synthesize pyrazoline, isoxazoline and pyrimidine derivatives (3-10). Thiosemicarbazone and semicarbazone (11, 17) were utilized to synthesize other new triazolethiones, thiadiazole and selenadiazole derivatives (11-19). Some new spiro derivatives (22-25) were synthesized by the reaction of chalcone (21) of 1 and isatine with hydrazines, hydroxyl amines and thiourea. Also, The reaction of 1 with cyanoacetyl hydrazine gave the hydrazide-hydrazone derivative 26, which was allowed to react with aromatic aldehydes and α-cyanocinnamonitrile to afford coumarine and substituted pyridine derivatives (28, 29). The structures of all the new compounds have been established on the basis of their analytical and spectral data. Twenty two of the synthesized compounds were also evaluated for their antibacterial and antifungal activity against various strains of bacteria and fungi and most are found to possess promising antimicrobial activity when compared with Chloramphenicol and Clotrimazol

Multi-Component One-Pot Synthesis and Antimicrobial Activities of 3-Methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydro-pyrazolo[5,4-b]pyrimidino[5,4-e]pyridine-5-one and Related Derivatives

The synthesis of 3-methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydropyrazolo[5,4-b] pyrimidino[5,4-e]pyridine-5-one (6) was achieved by two different one-pot multi-component synthesis (one-pot three-component and one-pot four component synthesis). Mono and dialkylation of 6 under different conditions gave compounds 7–11. The hydrazine 12 produced from reaction of 9 with N2H4 was subjected to reactions with some aromatic aldehydes, ethyl acetoacetate, acetyl acetone, ethyl cyanoacetate and triethyl orthoformate to give 13–17, respectively. Compound 12 upon reaction with CS2, nitrous acid, benzoin, chloroacetone and phenacyl bromide gave 18,20,21,22. Alkylation of 18 with ethyl iodide, ethyl chloroacetate and phenacyl bromide gave 19a–c. The antibacterial and antifungal activities of selected derivatives were evaluated

Multi-Component One-Pot Synthesis and Antimicrobial Activities of 3-Methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydro-pyrazolo[5,4-b]pyrimidino[5,4-e]pyridine-5-one and Related Derivatives

The synthesis of 3-methyl-1,4-diphenyl-7-thioxo-4,6,8,9-tetrahydropyrazolo[5,4-b] pyrimidino[5,4-e]pyridine-5-one (6) was achieved by two different one-pot multi-component synthesis (one-pot three-component and one-pot four component synthesis). Mono and dialkylation of 6 under different conditions gave compounds 7–11. The hydrazine 12 produced from reaction of 9 with N2H4 was subjected to reactions with some aromatic aldehydes, ethyl acetoacetate, acetyl acetone, ethyl cyanoacetate and triethyl orthoformate to give 13–17, respectively. Compound 12 upon reaction with CS2, nitrous acid, benzoin, chloroacetone and phenacyl bromide gave 18,20,21,22. Alkylation of 18 with ethyl iodide, ethyl chloroacetate and phenacyl bromide gave 19a–c. The antibacterial and antifungal activities of selected derivatives were evaluated

Theoretical and experimental investigations on the structure and vibrational spectra of 6-amino-3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]pyridine-5-carboxylic acid and 6,7-dihydro-3-methyl-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile

The solid phase FT-IR and FT-Raman spectra of 6-amino-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid (PYRPCA) and 6,7-dihydro-3-methyl-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (PYRPCN) were recorded in the region 4000–400 cm-1. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimization and force field calculations based on the density functional theory (DFT) using standard B3LYP, BLYP and ab initio RHF methods with 6-31G* basis set and were scaled using a recommended set of scaling factors yielding fairly good agreement between the observed and calculated frequencies. Based on the present good quality, the scaled quantum mechanical (SQM) force field, a reliable description of the fundamentals of PYRPCA and PYRPCN, was provided. The calculations predicated a predominance of different tautomers in PYRPCA and keto-enol tautomers in PYRPCN. For PYRPCA, the most stable conformer is stabilized by intramolecular hydrogen bonding. The characteristic of the hydrogen bonding is its strengthening effect on the conjugation of the NH2 and COOH groups with the pyridine ring

Theoretical and experimental investigations on the structure and vibrational spectra of 6-amino-3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]pyridine-5-carboxylic acid and 6,7-dihydro-3-methyl-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile - Supplementary Material

N/