Synthesis of important new pyrrolo[3,4-c]pyrazoles and pyrazolyl-pyrrolines from heterocyclic β-ketonitriles

Treatment of heterocyclic β-ketonitriles 1a,b with hydrazine hydrate and phenylhydrazine afforded the hydrazine derivatives 2a-d which cyclized in PPAinto pyrrolo[3,4-c]pyrazoles 3a-d. Reaction of 1a,b with cyanoacetohydrazide furnished the cyanoacetyl pyrrolo[3,4-c]pyrazoles 4a,b. The hydrazine 2c reacted with β-diketone and β-ketoesters to afford pyrazolyl-pyrrolines 5-7. Also the later hydrazine reacted with some D-aldoses and aceteophenone to give the corresponding hydrazones 10-12 and hydrazine carboxamide derivatives 15a,b respectively.