Reactions of 2‐acyl‐1,3‐indandiones with monosubstituted hydrazines and hydrazides

Methyl‐ and phenylhydrazines react with 2‐(diphenylacetyl)‐1,3‐indandione ( 1 ) to yield respectively the 1‐(methylhydrazone) and the 1‐(phenylhydrazone) of 2‐(diphenylacetyl)‐1,3‐indandione ( 2a and 2b ). In comparison, acetic and benzoic acid hydrazides react with 1 to give respectively the α‐(acetylhydrazone) and the α‐(benzoylhydrazone) of 2‐(diphenylacetyl)‐1,3‐indandione ( 3a and 3b ). Cyclization of 2a and 2b gives 2,3‐disubstituted indeno[1,2‐ c ]pyrazol‐4(2 H )‐ones ( 7a and 7b ). Cyclization of 3a and 3b , followed by methylation, gives 1‐methyl‐ and 2‐methyl‐3‐(diphenylmethyl)indeno[1,2‐ c ]pyrazol‐4(1 and 2 H )‐ones ( 9a and 9b ). 2‐Isovaleryl‐1,3‐indandione reacts with phenylhydrazine to give directly 3‐isobutyl‐1‐phenylindeno[1,2‐ c ]‐pyrazol‐4(1 H )‐one ( 10 ).