Highly efficient one-pot synthesis of fused pyrimidones from 2-heteroaryl amines and Morita–Baylis–Hillman carbonates via intermolecular cyclocondensation

A highly selective and efficient cyclocondensation reaction for construction of various 3-substituted-2H-pyrido[1,2-a]pyrimidin-2-ones and related fused pyrimidones from allylic carbonates and 2-heteroaryl amines has been developed. The transformation involves one-pot sequential aza-Michael addition, intramolecular acyl substitution, and [1,3]-H shift. The method is catalyst free, eco-friendly, scalable, and completes within a short reaction time, with no work-up, no column purification, and demonstrate a broad functional group tolerance.