Design, Synthesis and Anticancer Activity of Aza Heterocycles Containing Gallate Moiety (Part III)

Pyrazole-carboxaldehydes as versatile precursors for different pyrazole-substituted heterocyclic systems

“…Under various conditions, the Hantzsch condensation reaction of pyrazole-4-carboxaldehyde 2 with βketoester 64 and ammonium acetate or ammonia afforded the corresponding dihydropyridines 182. 131,[176][177][178][179][180][181][182][183] Similarly, N-aryl-1,4-dihydropyridines 183 were prepared by heating the 1,3-diphenyl-1H-pyrazole-4carboxaldehyde 2, ethyl acetoacetate/acetylacetone 64 and substituted anilines 184 165 Also, it was reported that the cyclocondensation of pyrazole-carboxaldehyde 2 with urea 120 or thiourea 184 120,185 and ethyl cyanoacetate 64 in the presence of sodium ethoxide 120 or potassium carbonate 185 gave the corresponding 2-oxo(thioxo)pyrimidine derivatives 185 (Scheme 79).…”

“…The reaction of α,β-unsaturated ketone 42 with thiourea 184 in the presence of sodium ethoxide solution at reflux was reported to give either the corresponding pyrimidine derivatives 186, 104,114,115,165 187, 141,157 or 188 186 (Scheme 80). On the other hand treatment of chalcones 42 with guanidine hydrochloride or guanidine sulfate 184 at reflux afforded pyrimidin-2-amines 189 104,109,114,115 (Scheme 81).…”