SELECTIVE HYDROSILYLATION OF ALKYNES CATALYZED BY AN ORGANOYTTRIUM COMPLEX

The organoyttrium complex Cp2YCH3 . THF (Cp* = C(5)Me(5)) has been sh own 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 phenylsilan e to the alkyne. The reaction of various unsymmetrically substituted i nternal alkynes results in a regioselective hydrosilylation reaction t hat places the silane at the less hindered carbon of the alkyne. A var iety of functional groups, e.g., halides, amines, protected alcohols, and trisubstituted olefins, are tolerated by the reaction conditions w ith no decrease in yield.