Access to Functionalized E‑Allylsilanes and E‑Alkenylsilanes through Visible-Light-Driven Radical Hydrosilylation of Mono- and Disubstituted Allenes

A visible-light-driven radical hydrosilylation of allene has been achieved by using eosin Y as the photocatalyst, with thiol and base as additives. Depending on allenes, two types of adducts with E-selectivity were obtained. It was demonstrated that monosubstituted nonarylated allenes reacted to give linear E-allylsilanes, while 1,3-disubstituted electron-deficient allenes afforded E-alkenylsilanes. A radical mechanism was proposed to account for the chemo-, regio-, and stereoselective formation of these functionalized silicon-containing compounds.