An Efficient Single Step Synthesis of Pyridazine, Pyrazolo[5,1-c]-1,2,4-triazine, 1,2,4-Triazolo[5,1-c]-1,2,4-triazine and 1,2,4-Triazino[4,3-a]benzimidazole Derivatives

Coupling of E-1-(1-methylbenzimidazol-2-yl)-3-(N,Ndimethylamino)prop-2-enone (1) with the arenediazonium salt gave hydrazonopropanal 5 which underwent cyclocondensation with active methylene compounds to afford substituted pyridazin-6-imine 8 and 11.The enaminone 1 coupled also with the diazonium salts prepared from aminopyrazole, aminotriazole and 2-amino-1H-benzimidazole to afford pyrazolo[5,1-c]-l,2,4triazine 15, 1,2,4-triazolo[5,1-c]-1,2,4-triazine 19, 1,2,4-triazino[4,3a]benzimidazole 23 derivatives, respectively.