A novel and stereodefined synthesis of (E)-β-ethoxycarbonylvinylsilanes: regio- and stereo-controlled hydroethoxycarbonylation of silylacetylenes by palladium(II) catalysis

Abstract

[PdCl₂(dppf)]–SnCl₂·2H₂O catalysed hydroethoxycarbonylation of silylacetylenes 1 provided a novel and convenient synthesis of (E)-β-ethoxycarbonylvinylsilanes 2. The reactions, carried out under mild conditions (90 °C. 20 kg cm^–2) gave the products 2 in excellent yields. This procedure tolerated the presence of chloro or ethoxycarbonyl substituents separated from the carbon-carbon triple bond in silylacetylene 1. α-Trimethylsilylmethylene-γ-butyrolactones 11, with an alkoxycarbonyl substituted vinylsilane moiety, were obtained in excellent yields by the reaction of tetrahydropyranyl ethers of 4-trimethylsilylbut-3-yn-1-ols 10. A reasonable mechanism for the regioand stereo-controlled hydroethoxycarbonylation is described.