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

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. [ABSTRACT FROM AUTHOR]