The generality of two different courses of cyclization reactions for 4-substituted 5-amino-4- cyano-4H-imidazoles (5) is demonstrated. One results from treatment of 5 with formamidine in a" translocative rearrangement" that leads to 8-substituted 4-aminoimidazo [l, 5-a]-1, 3, 5- triazines (7). The other results from treatment with dimethyl acetylenedicarboxylate, without rearrangement, that leads to 8-substituted 8-cyano-8H-imidazo [1, 5-a] pyrimidin-4-ones ( ...