Synthesis of Linear Allylsilanes via Molybdenum-Catalyzed Regioselective Hydrosilylation of Allenes

A simple molybdenum-based catalytic system for hydrosilylation of allenes has been developed. The reactions of mono- and disubstituted allenes with secondary and tertiary silanes proceeded smoothly and selectively to afford linear allylsilanes. The origin of the unprecedented linear selectivity was investigated by density functional theory studies to reveal that the reaction consists of the following steps: (1) concerted hydromolybdation/Si–H oxidative addition from a Mo­(CO)₄/allene/silane adduct to form (π-allyl)­molybdenum, (2) allyl rotation from the initially formed (π-allyl)­molybdenum to a thermodynamically more stable isomer, and (3) reductive elimination at the less-hindered allyl carbon to afford a linear allylsilane