Stereoselective reduction of α-alkoxycarbonylketene dithioacetals with the use of Me2Cu(CN)Li2

α-Alkoxycarbonylketene dithioacetals (1) were smoothly reduced by the higher order cyanocuprate Me2Cu(CN)Li2 at –20 °C to the corresponding vinyl sulphides (2) in high yields, with high stereoselectivity and generality.