Organophotocatalytic Strain-Releasing Hydrosilylation of Bicyclo[1.1.0]butanes with Silylboronates

Herein, the visible-light-driven strain-releasing hydrosilylation of bicyclo[1,1,0]butanes (BCBs) with silylboronates is disclosed. Using thioxanthen-9-one (TXT), K 2 CO 3, and blue LEDs as the catalytic system, the first hydrosilylation of BCBs via silyl radicals added across C–C σ bonds to synthesize valued cyclobutanes was established with good to excellent yields. Mechanistic study confirmed this transformation included a radical process, and the silyl radicals were generated via single-electron transfer (SET) oxidation of activated silylboronates mediated by photocatalysis. Deuterium (D) labeling experiments verified that a hydrogen atom transfer (HAT) process occurred from the protic solvent to the product.