Oxidant promoted 1,3dipolar cycloaddition of benzimidazolium ylides to alkenes for preparation of 4Hpyrrolo1,2abenzimidazole

An oxidant promoted 1,3dipolar cycloaddition of benzimidazolium ylides to alkenes was developed for the preparation of 4Hpyrrolo1,2abenzimidazole 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, CrO3Et3N has been proved to be a more effective dehydrogenating reagent than MnO2or tetrakispyridine cobalt II dichromate TPCD in this procedure.