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.
Key words
benzimidazoles - green synthesis - rapid condensation - heterocyclization - 1,2-diaminoarenes
- catalyst-free reactions