A reaction of γ-chalcogen-substituted prop-2-ynyl cations with mild nucleophiles

Abstract
γ-Chalcogen-substituted prop-2-ynyl cations are generated by the reactions of diethyl acetals 1 and 2 with BF3–Et2O and react with various mild nucleophiles without isomerisation to allenyl cations to afford the prop-2-ynylated products 3a–e and 5a–c in good yields.