Photoinduced transition metal-free borylation of aryl halides in an aqueous phase†

Abstract

A green photoinduced borylation of aryl halides catalyzed by 1-methylbenzimidazole in an aqueous phase is reported. The reaction proceeds efficiently under transition metal-free conditions at room temperature and is highlighted by operational simplicity, scalability, broad substrate compatibility, and good functional group tolerance, providing a practical and environmentally benign access to aryl boronic esters. Mechanistic experiments show that photoinduced homolytic cleavage of the activated diboron reagent constitutes a key step in this reaction.