Nickel-catalyzed silaborative dimerization of alkynes

Double insertion of alkynes into the Si-B bond of (dimethylphenylsilyl)pina colborane proceeded in the presence of nickel(0) catalysts to give cis,cis- 1-silyl 4-boryl-1,3-butadiene derivatives in a regio- and stereoselective m anner. Involvement of (silyl)(2-boryl-1-alkyl-vinyl)nickel(II) intermediate s in the silaborative dimerization reaction was suggested by the regiochemi cal preference as well as on the basis of reactions of the corresponding ge rmylborane with alkynes in the presence of Ni, Pd, and Pt catalysts.