Synthesis of Some Pyrazole Derivatives from 5-Chloro- and 5-Azido-1,3-diphenyl-1H-pyrazole-4-carbaldehydes

Abstract

N-[(5-Azido-1,3-diphenyl-1H-pyrazole-4-yl)methylene]-N-arylamines (4a-c) and N-[(5-Substituted-1,3-diphenyl-1H-pyrazole-4-yl)methylene]hydrazides (5a-e) were prepared from 5-azido-1,3-diphenyl-1H-pyrazole-4-carbaldehyde (3)  and 5-chloro-1,3-diphenyl-1H-pyrazole-4-carbaldehyde (2), respectively. Thermolysis of (4a-c) and (5d-e) afforded 5-arylamino-1,3-diphenyl-1H-pyrazol-4-carbonitriles (8a-c) and N-(4-cyano-1,3-diphenyl-1H-pyrazol-5-yl)hydrazides (13a,b), respectively. N-[2-(5-Chloro-1,3-diphenyl-1H-pyrazol-4-yl)-4-oxo-thiazolidin-3-yl]amides (14a,b)  and 3-acetyl-2-(5-chloro-1,3-diphenyl-1H-pyrazol-4-yl)-5-aryl-2,3-dihydro-1,3,4-oxadiazoles  (15a,b)  were obtained from N-[(5-chloro-1,3-diphenyl-1H-pyrazole-4-yl)methylene]hydrazides (5a,b). 5-Azido-1,3-diphenyl-1H-pyrazol-4-carbaldehyde (3) gave unexpectedly 1-(1,3-diphenyl-1,6-dihydropyrrolo-2,3-c]pyrazol-5-yl)ethan-1-one (17).