Asymmetric Radical Oxyboration of β‐Substituted Styrenes via Late‐Stage Stereomutation

Abstract Herein, we report an unprecedented copper‐catalyzed highly enantio‐ and diastereoselective radical oxyboration of β ‐substituted styrenes. The lynchpin of success is ascribed to the development of a late‐stage stereomutation strategy, which enables enantioenriched cis ‐isomers among a couple of early‐generated diastereomers to be converted into trans ‐isomer counterparts, thus fulfilling high diastereocontrol; while the degree of enantio‐differentiation is determined by the borocupration process of the C=C bond. This reaction provides an efficient protocol to access enantioenriched trans ‐1,2‐ dioxygenation products. The value of this method has further been highlighted in a diversity of follow‐up stereospecific transformations and further modifying complex molecules.