Synthesis of new 5-N-pyrazolyl amino acids, pyrazolopyrimidines and pyrazolopyridines derivatives

Reaction of ketene derivatives (1a,b) on treatment with 4-amino-1-phenyl-2, 3-dimethyl pyrazolin-5-one gives compounds (2a,b) which react with hydrazin e to afford 1-phenyl-2,3 dimethyl-4-[3-(5-amino-4-substituted)-1H-pyrazolyl amino]pyrazolin-5-one (3a,b). Compounds (3a,b) on treatment with Boc. amino acids derivatives, acetic anhydride, ethyl acetoacetate and aldehydes affo rded (4a-h), (5a-h), (6-10), (11a,b), respectively. Interaction of (9) or ( 10) with acetohydrazide, hydrazines, and then with p-bromobenzaldehyde affo rded compounds (13), (14a,b) and (15), respectively. Interaction of (3a) wi th thioglycollic acid afforded pyrazolopyridines derivatives (16).