摘要:
1,1-Dichloro-2-alkynes R1C=CCHCl2 (4a-g; R1 = Me, n-Pr, c-Pr, t-Bu, Ad, Nor, Ph) were synthesized with yield of 50-75% by chlorination with PCl5 of formylacetylenes (3a-g), prepared by oxidation of propargyl alcohols (1a-d) with CrO3.Py.HCl complex or acidolysis of propargyl acetals (2a-c) in the presence of catalytic quantities of pyridine; the corresponding alkynylchlorocarbenes, R1C=CCCl (5a-g) were generated from them with powdered KOH in a two-phase system or t-BuOK. The latter were trapped by olefins with formation of 1-chloro-1-alkynylcyclopropanes (6a-t) with yields of up to 90%.