Oxidant promoted 1,3-dipolar cycloaddition of benzimidazolium ylides to alkenes for preparation of 4H-pyrrolo[1,2-a]benzimidazole

✍ Scribed by Bingxiang Wang; Jiaxin Hu; Xuechun Zhang; Yuefei Hu; Hongwen Hu

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2000
• Tongue: English
• Weight: 377 KB
• Volume: 37
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570370620

✦ Synopsis

Abstract

An oxidant promoted 1,3‐dipolar cycloaddition of benzimidazolium ylides to alkenes was developed for the preparation of 4__H__‐pyrrolo[1,2‐a]benzimidazole derivatives in moderate yields under mild conditions. In the presence of a suitable oxidant, the most commercially available “normal” alkenes, instead of alkynes or “abnormal” alkenes, could be used as dipolarophiles successfully. Moreover, CrO~3~/Et~3~N has been proved to be a more effective dehydrogenating reagent than MnO~2~ or tetrakispyridine cobalt (II) dichromate (TPCD) in this procedure.