A new general method for the generation of (alk-1-ynyl)halocarbenes by base solvolysis of 3-substituted 1,1,1,3-tetrahalopropanes

The (alk-1-ynyl)halocarbenes 4 have been generated from 3-substituted 1,1,1,3-tetrahalopropanes 1 via elimination of three molecules of hydrogen halide by treatment with Bu^tOK or with alkali metal hydroxides under phase-transfer catalysis conditions and have been trapped by alkenes to form 1-(alk-1-ynyl)-1-halocyclopropanes 5 in 40–70% yields.