Visible-Light-Induced, Metal-Free Carbene Insertion into B–H Bonds between Acylsilanes and Pinacolborane

Carbene insertion reactions with B–H bonds are a challenging but promising method for the synthesis of organoboranes. Herein, we report visible-light-induced B–H insertions of HBpin with acylsilane. This metal-free and operationally simple reaction proceeds in an atom-economical way with broad substrate scope under mild reaction conditions, affording a variety of important α-alkoxy­organo­boronate esters in quantitative yields. Control experiments and density functional theory calculations suggest that the siloxy­carbene generation from the T₁ state of acyl­silane and the carbene insertion into the B–H bond occurred in a concerted manner.