Heterocyclic synthesis via enaminonitriles:: An efficient, one step synthesis of some novel azolo[1,5-a]pyrimidine, pyrimido[1,2-a]-benzimidazole, pyrido[1,2-a]benzimidazole pyrimidine and pyrazole derivatives

some novel pyrazolol[1,5-a]pyrimidines 5a-f, 10a,b, 1,2.4-triazolo[1,5-a]-pyrimidine (12), and pyrimido[1,2-a]benzimidazole 18 could be synthesized by reacting 3-(4-chlorophenyl)-2-(N,N-dimethylamino)methylene-3-oxopropanenitrile (2) with 5-amino-3- and/or 4-substituted-1H-pyrazoles 3a-f and 9a,b, 3-amino-1,2,4-triazole (11) and 2-aminobenzimidazole (14), respectively, The reaction of a with 1H-benzimidazol-2-ylacetonitrile (19) afforded the pyrido[1,2-a]benzimidazole 20, On the other hand, the reaction of 2 with guanidine, hydrazine. and phenyl hydrazine afforded the pyrimidine 24, and the pyrazoles 27, 28. respectively. However, the reaction of 2 with hydroxyl amine did not afford the isoxazole 32.