Electrochemical oxidative dehydrogenation of hydrosilanes to generate silyl radicals: an efficient method for the construction of Si–O/Si–Si bonds utilizing a recyclable ionic liquid catalyst†

Abstract

A highly efficient and sustainable approach was developed for the construction of Si–O/Si–Si bonds, through the electrochemical oxidative dehydrogenation of hydrosilanes with O-nucleophiles (e.g. phenols, naphthols, alcohols, and H₂O) or hydrosilane self-condensation. The protocol employs a highly electrically conductive and recyclable ionic liquid as a catalyst, thus eliminating the need for external electrolytes and hydrogen atom transfer (HAT) agents. The ionic liquid could be easily recovered and reused for at least eight cycles with consistent performance. Notably, this electrochemical method exhibits a broad substrate scope and high functional-group compatibility (66 examples, up to 96% yield). Initial mechanistic studies show that silicon radicals are generated via the process of hydrogen atom transfer between bromine radicals and silanes, and KIE experiments demonstrate that Si–H bond cleavage is the rate-determining step of the reaction.