Microwave-assisted C-H bond activation: a rapid entry into functionalized heterocycles.

Microwave irradiation strongly accelerates the rhodium-catalyzed intramolecular coupling of a benzimidazole C−H bond to pendant alkenes. The cyclic products were formed in moderate to excellent yields with reaction times less than 20 min. Additionally, the use of microwave irradiation allowed the reactions to be performed without any solvent purification and with minimal precautions to exclude air.