Simple preparation of fused pyrrolo[2,3-b]pyrrolidinones and pyrrolo[2,3-c]pyridazinones1

Abstract

4-Methyl-4-(dimethoxymethyl)pyrans 4b, 4c and 15, prepared from cyclohexane-1,3-diones 1 or 4-hydroxycoumarin 14, pyruvaldehyde dimethyl acetal 2b and malononitrile 3, are subjected to hydrolysis with HCl to give fused furofuranones 5 and 16, which are treated with amines or hydrazines to give fused pyrrolopyrrolidinones 9 and 18 and pyrrolopyridazinones 12.