Synthesis of benzimidazoles from 1,1-dibromoethenes

A mild and efficient method for the preparation of substituted benzimidazoles from 1,1-dibromoethenes and o-diaminobenzenes is described. The reaction employs DABCO as the base and NMP as the solvent. A variety of substitutions on both 2-aryl-1,1-dibromoethenes and o-diaminobenzenes are tolerated. This new procedure is carried out under mildly basic conditions, which may provide a complementary route to the existing preparations of benzimidazoles.