A nitrile-stabilized ammonium ylide as a masked C–CN synthon in heterocyclization with amidine–imine: 3-component assembly to fused pyrimidine scaffolds

A unique reactivity of a nitrile-stabilized quaternary ammonium ylide as a masked C-C[double bond, length as m-dash]N synthon in contrast to its usual sigmatropic rearrangement has been demonstrated. Its reaction with 2-aminopyridine-derived aldimine undergoes electronically-assisted nucleophilic additions and Hofmann elimination, and provides a new method to access fused pyrimidines.