Stereochemistry of chlorination and chloroiodination of alkylphenylacetylenes by CuCl2

Abstract

Reaction of alkylphenylacetylenes, PhCCR (R = H or alkyl)(1), with CuCl2–LiCl or CuCl2–I2 in acetonitrile gives the corresponding dihalogenoalkenes in good yields; E-addition is favoured except in the chlorination of (1, R = But) where Z-addition predominates.