Synthesis of 4-aryl-4,7,8,9-tetrahydro-6H-pyrazolo[3,4-b]quinolin-5-ones

Abstract

Reaction of 5-amino-3-methyl-1-phenylpyrazole (1a) and 5-amino-3-(4-chlorophenyl)-1H-pyrazole (1b) with dimedone (2) and p-susbstituted benzaldehydes 3 in ethanol, afforded in all cases tricyclic linear 4-aryl- 7,7-dimethyl-4,7,8,9-tetrahydro-6H-pyrazolo[3,4-b] quinolin-5-ones (4a-j) in good yields. The linear structures and hence the regiospecificity of the reaction were established by nmr measurements.