Synthesis of unsymmetrical 1,3-substituted-1,3-dihydro-benzimidazolones via copper-catalyzed C–N coupling under visible light.

Although photoinduced copper catalysis for carbon–nitrogen (C–N) amine bond formation with alkyl/aryl halides has been developed, the potential of copper catalysis for the synthesis of 1,3-substituted benzimidazolone molecules remains mostly unexplored. We herein report for the first time that unsymmetrical 1,3-substituted-1,3-dihydro-benzimidazolones can be readily prepared from monosubstituted benzimidazolones with primary alkyl, allyl, and benzyl bromides in the presence of a catalytic amount of copper(I) bromide and visible light. The catalytic system was optimized and a library of benzimidazolone products were converted in overall great yields up to 99%, demonstrating the utility of this approach for practical and green synthesis schemes. [ABSTRACT FROM AUTHOR]