Improved synthesis of substituted pyrido[2,3-d]pyrimidinediones

An improved methodology for the synthesis of substituted pyrido[2,3-d]pyrimidinediones from 6-aminouracils and the corresponding enaminone has been developed which provides high yields via an operationally simple process. The method has been extended to encompass a range of electron-rich enaminones, a substrate class that does not perform well under the standard conditions.