Abstract: | 1,1-Dichloro-2-alkynes R1C CCHCl2 (4a–g; R1=Me, n-Pr, c-Pr, t-Bu, Ad, Nor, Ph) were synthesized with yields 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%.See 1] for Communication 1.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1128–1135, May, 1992. |