New Synthesis of Imidazo(1,2-a)- and Pyrimido(1,2-a)pyrimidines.

Abstract 6-Aryl-4-oxo-2- thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitriles (1) reacted with bromomalo-nonitrile(2) to give 3-amino-7-aryl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarbonitriles (3a-c). The latter compounds reacted with either formic acid, formamide or ammonium thiocyanate to yield the 7-aryl-9-oxo-4-substituted-thiazolo[3,2-a:4,5-d′]dipyrimidine-8-carbonitrile derivatives (4–6), respectively. Compounds (3a-c) could be converted into 7-aryl-3-amino-1-benzyl-5-oxo-5H-imidazo[1,2-a]pyrimidine-6-carbonitriles (8) and 4-amino-8-aryl-2,6-dioxo-3-substituted-1,2-dihydro-6H-pyrim-ido[1,2-a]pyrimidn-7-carbonitriles (9) by treatment in boiling ethanol with benzylamine and cyclic secondary amines, respectively.