Solid acid catalyzed reaction of aminals (1) under bar with methyl 3-aminoc
rotonate (2) under bar affords dimethyl 4-aryl-2,6-dimethyl-1,4-dihydropyri
dine-3,5-dicarboxylates (3) under bar. 2-Methyl-4H-pyrido[1,2-a]-pyrimidin-
4-one (4) under bar is formed from 2-aminopyridine moiety of the aminals.