Preparation of Alkyl Boronic Esters Using Radical‐Polar Crossover Reactions of Vinylboron Ate Complexes

It is shown here that carbon radicals add efficiently to vinylboron ate complexes and that their adduct radical anions undergo radical-polar crossover: A 1,2-alkyl/aryl shift from boron to the α-carbon sp2 center provides secondary or tertiary alkyl boronic esters.