Regioselective synthesis of some novel pyrazoles, isoxazoles, pyrazolo3,4-dpyridazines and isoxazolo3,4-dpyridazines pendant to benzimidazole

摘要

2-Acetyl-1-methyl-1H-benzimidazole reacts with dimethylformamide-dimethyl-acetal (DMF-DMA) to afford the corresponding E-1-(1-methyl-1H-benzimidazol-2-yl)-3-N,N-dimethylaminoprop-2-enone. The latter compound reacts regioselectively with some nitrilimines and nitrile oxides to afford the corresponding pyrazole and isoxazole derivatives, respectively. These reaction products react with hydrazine hydrate to give the novel pyrazolo3,4-dpyridazine and isoxazolo3,4-dpyridazine derivatives, respectively.