Samarium Diiodide‐Mediated Radical Borylation of Alkyl Bromides

The samarium diiodide‐mediated radical borylation of alkyl bromides has been accomplished. Direct coupling of alkyl bromides and bis(pinacolato)diboranes with samarium diiodide reagents under ligand‐free and base‐free conditions affords a variety of alkyl boronic esters in good to excellent yields. Broad substrate scope and excellent functional group tolerance have been demonstrated for this radical borylation approach. Mechanistic studies and density functional theory computations have been conducted to gain insight into the reaction pathway for this novel functionalization approach. This general approach is expected to stimulate further progress in the chemistry of lanthanide(II) reagents.