A metal- and solvent-free bromination of electron-deficient allyl and benzyl C–H bonds

Abstract

Bromination reactions of C(sp³)–H bonds at allylic and benzylic positions have been widely applied in the synthesis of pharmaceuticals and functional materials. However, traditional Wohl–Ziegler bromination reactions often involve harsh reaction conditions and afford low to moderate yields. In particular, direct bromination of electron-deficient allylic and benzylic C–H bonds has been rarely reported. Herein, we present an NHPI-catalyzed bromination method for electron-deficient allylic and benzylic C–H bonds. This method is metal- and solvent-free, exhibits high site selectivity and good yields, operates under mild conditions, and is operationally simple.