A facile and efficient [4 + 2] annulation reaction of sulfur ylides: access to N-fused benzimidazoles

A facile and efficient approach to synthesize a series of new N-fused benzimidazoles in good yield is reported for the first time using the [4 + 2] cascade cycloaddition of 2-substituted benzimidazole derivatives and a bromoethylsulfonium salt, which is easily prepared on a large scale and is stably crystalline, under mild reaction conditions.