Stereodivergent Synthesis of β-Heteroatom-Substituted Vinylsilanes by Sequential Silylzincation-Copper(I)-Mediated Electrophilic Substitution.

Sulfur-, oxygen-, and phosphorus-substituted terminal alkynes undergo regio- and stereoselective silylzincation by reaction with (Me₂PhSi)₂Zn, (Me₃Si)₃SiH/Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn. The addition across the C-C triple bond always occurs with β-regioselectivity but the stereoselectivity is tunable: (Me₂PhSi)₂Zn for cis and (Me₃Si)₃SiH/Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn for trans. The procedures making use of the zinc reagents (Me₂PhSi)₂Zn and [(Me₃Si)₃Si]₂Zn can be combined in one-pot with a subsequent stereoretentive copper(I)- mediated electrophilic substitution of the intermediate C(sp²)-Zn bond. These stereodivergent protocols offer a regio- and stereoselective access to trisubstituted vinylsilanes decorated with sulfur-, oxygen-, and phosphorus substituents with either double-bond geometry. [ABSTRACT FROM AUTHOR]