Photochemical Radical C–H Halogenation of Benzyl N‐Methyliminodiacetyl (MIDA) Boronates: Synthesis of α‐Functionalized Alkyl Boronates

α‐Haloboronates are useful organic synthons that can be converted to a diverse array of α‐substituted alkyl borons. Methods to α‐haloboronates are limiting and often suffer from harsh reaction conditions. Reported herein is a photochemical radical C‐H halogenation of benzyl N‐methyliminodiacetyl (MIDA) boronates. Fluorination, chlorination, and bromination reactions were effective by using this protocol. Upon reaction with different nucleophiles, the C−Br bond in the brominated product could be readily transformed to a series of C−C, C−O, C−N, C−S, C−P, and C−I bonds, some of which are difficult to forge with α‐halo sp2‐B boronate esters. An activation effect of B(MIDA) moiety was found. A photochemical radical C−H halogenation of benzyl N‐methyliminodiacetyl (MIDA) boronates is described. Fluorination, chlorination, and bromination reactions were all effective using this method. The brominated products serve for the synthesis of α‐functionalized alkyl boron compounds. By virtue of coordination saturation of the MIDA boron moiety, some synthetically challenging α‐substituted alkyl borons are also accessible.