SELECTIVE HYDROSILYLATION OF ALKYNES CATALYZED BY AN ORGANOYTTRIUM COMPLEX

The organoyttrium complex Cp*2YCH3 . THF (Cp* = C(5)Me(5)) has been shown to be an effective precatalyst for the hydrosilylation of internal alkynes. The reaction with symmetrically substituted alkynes results in a single stereoisomer as the product of cis addition of phenylsilane to the alkyne. The reaction of various unsymmetrically substituted internal alkynes results in a regioselective hydrosilylation reaction that places the silane at the less hindered carbon of the alkyne. A variety of functional groups, e.g., halides, amines, protected alcohols, and trisubstituted olefins, are tolerated by the reaction conditions with no decrease in yield.