Auxiliary‐Based Stereoconvergent Transition Metal‐Free Cross‐Electrophile Couplings of α‐Iodoboronic Esters

Chiral boronic esters are highly valuable building blocks in organic chemistry and related fields, allowing access to structurally diverse libraries, including those of drug candidates. Herein, stereoselective cross couplings of α ‐iodoboronic esters with various commercial electrophiles are reported. These stereoconvergent coupling reactions proceed via iodine‐metal exchange and subsequent stereoselective capture of the generated α ‐boryl organometallic species without the use of a transition metal catalyst. The presented reactions allow the α ‐silylation, α ‐borylation, and α ‐methylborylation of boronic esters using a common chiral auxiliary.