Borylation of Stable C(sp 3 )-O Bonds of Alkyl Esters over Supported Au Catalysts.

We report herein that supported gold catalysts efficiently promote the borylation of stable C(sp 3 )-O bonds of alkyl esters. The use of a disilane as an electron source and gold nanoparticles as a single-electron transfer catalyst is the key to generating alkyl radicals via the homolysis of stable C(sp 3 )-O bonds, thereby enabling cross-coupling between bis(pinacolato)diboron and linear and cyclic alkyl esters to afford the diverse alkyl boronates.