Base-catalyzed synthesis of bicyclic 4-aminopyrimidines from the reaction of dinitriles with mononitriles

A convenient method for the synthesis of bicyclic 4-aminopyrimidines is described, involving the reaction of dinitriles with mononitriles in the presence of catalytic potassium tert-butoxide. These reactions proceed via the Thorpe–Ziegler cyclization of the dinitrile to form an intermediate β-cyanoenamine, which then undergoes annulation with the mononitrile in situ.