Herein is reported a substantially improved synthesis of 2-substituted
benzimidazoles by condensation of 1,2-diaminoarenes and aldehydes using
methanol as the reaction medium. The developed method afforded moderate
to excellent yields (33-96%) at ambient temperature, displays high functional
group tolerance, is conducted open to air, and requires only one-minute
reaction time under catalyst- and additive-free conditions. Moreover, the
efficient protocol permits scale-up to multi-gram scale synthesis of
benzimidazoles and will become a method of choice when constructing such
heterocyclic systems
