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)<sub>4</sub>/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
