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

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

Crystal structure of 5-[2-(9H-carbazol-9-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione

The title compound, C16H13N3OS, comprises an oxadiazolethione ring bound to the N atom of an almost planar carbazole ring system (r.m.s. deviation = 0.0088 Å) through an ethylene chain. The oxadiazole ring is inclined to the the carbazole ring system by 40.71 (6)°. In the crystal, N—H...O, N—H...S, C—H...N and C—H...S hydrogen bonds combine with C—H...π(ring) and π–π contacts to stack the molecules along the b-axis direction

Synthesis of New Heterocycles from Reactions of 1-Phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonyl Azides

Two individual examples of pyrazolo[3,4-b]pyridine-5-carbonyl azides and hydrazides were reacted with various nucleophilic reagents. Different unexpected behaviors was observed. NMR, IR, mass spectra together with elemental analyses and X-ray structure analyses, were used to prove the structure of the obtained products.Peer reviewe

4-Amino-3-[2-(9H-carbazol-9-yl)ethyl]-1H-1,2,4-triazole-5(4H)-thione dimethyl sulfoxide monosolvate

In the crystal of the title compound, C16H15N5S·C2H6OS, both the 1,2,4-triazole derivative molecules and the disordered [refined occupancy ratio = 0.604 (1):0.396 (1)] dimethyl sulfoxide solvent molecules form centrosymmetric dimers, by way of pairwise N—H...S and C—H...O hydrogen bonds, respectively. In the crystal, the two types of dimer are connected by N—H...O hydrogen bonds, forming infinite chains parallel to [101]. The packing is assisted by π–π stacking and C—H...π(ring) and N—H...π(ring) interactions

Crystal structure of (E)-N-{[3-methyl-1-phenyl-5-(1H-pyrrol-1-yl)-1H-pyrazol-4-yl]methylidene}hydroxylamine

The title compound, C15H14N4O, crystallizes with two molecules in the asymmetric unit with similar conformations (r.m.s. overlay fit for the 20 non-H atoms = 0.175 Å). In the first molecule, the dihedral angles between the planes of the central pyrazole ring and the pendant phenyl and pyrrole rings are 42.69 (8) and 51.88 (6)°, respectively, with corresponding angles of 54.49 (7) and 49.61 (9)°, respectively, in the second molecule. In the crystal, the two molecules, together with their inversion-symmetry counterparts, are linked into tetramers by O—H...N hydrogen bonds. The tetramers form layers parallel to (211) through pairwise C—H...π interactions