A one-pot synthesis of pyrido[2,3-d]- and quinolino[2,3-d]pyrimidines

The in situ formed methylene derivatives of 1,3-dicarbonyl compounds; ethyl cyanoacetate; malononitrile and ketones; react with 6-amino-1,3-dimethylur acil as activated alkenyl derivatives, affording Michael adducts. The addut s simultaneously undergo cyclization to furnish pyrido[2,3-d]- or quinolino [2,3-d]pyrimidine derivatives in high yield.