γ-Trimethylsilyl-substituted allylzirconcenes in organic synthesis. Stereoselective synthesis of terminal 1,3-butadienes and functionalized vinylsilanes

γ-Trimethylsilyl-substituted allylzirconcenes, prepared by hydrozirconation of trimethylsilyl-substituted terminal allenes, react with aldehydes at the γ-position to give 1,3-butadienes in one step with good stereoselectivity and undergo conjugate addition to α,β-unsaturated aromatic ketones at the α-position to selectively afford functionalized vinylsilanes in the presence of catalytic CuBr·SMe2.