Stereodivergent Synthesis of β-Heteroatom-Substituted Vinyl-silanes by Sequential Silylzincation\textendashCopper(I)-Mediated Electrophilic- Substitution

International audience; 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.