Base Catalyzed Synthesis of Novel Fused-Imidazoles from N-Vinyl-1H-imidazole

Abstract

Syntheses of various classes of fused-imidazoles are reported. The key to their successful synthesis depends on the reaction of N-vinyl-1H-imidazole with the π-deficient compounds under basic conditions. Reaction of the target imidazole with 1,1,2,2-tetracyanoethylene and dimethyl acetylenedicarboxylate afforded pyrrolo[1,2-a]imidazoles. On the other site, reaction of the target imidazole with 2-dicyanomethyleneindane-1,3-dione, 2,3-dicyano-1,4-naphthoquinone gave indanylimidazolo- [1,2-a]azepine and imidazolo[2,1-a]phenanthridine derivatives, respectively. Under basic reaction condition, various classes of imidazolo[2,1-a]isoquinolines were obtained by the reaction of N-vinyl- 1H-imidazole with 2,3,5,6-tetrachloro-1,4-benzoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 3,4,5,6-tetrachloro-1,2-benzoquinone.