A new, general route to 1-chloro-1-ethynylcyclopropanes via chloro(trimethylsilylethynyl)carbene

A new, general route to 1-chloro-1-ethynylcyclopropanes 6 has been developed via cycloaddition of previously unknown chloro(trimethylsilylethynyl)carbene 4b to olefins with formation of the corresponding cyclopropanes 5a–f in 35–65% yield and subsequent removal of the trimethylsilyl group under the action of KF·2H₂O in aqueous DMF to give cyclopropanes 6 in up to 80% yield.