Copper-mediated Nucleophilic Displacement Reactions of 1-Haloalkynes. Halogen-Halogen Exchange and Sulfonylation

摘要

Some copper(I) and (II) compounds have been found to act as efficient reagents for the nucleophilic displacement of 1-haloalkynes. Copper(I) iodide smoothly transforms 1-bromoalkynes (2) into 1-iodoalkynes (1) which, on further treatment with copper(II) bis(arenesulfinate), are readily converted to the corresponding alkynyl aryl sulfones (4). The kinetic data of the halogen exchange between (4-chlorophenyl)ethynyl bromide (2d) and CuI have shown that the reaction is linearly dependent on the concentrations of both compounds. A mechanistic pathway involving the single electron transfer between 1-haloalkynes and copper(I) salt has been proposed for the present copper-assisted halogen exchange reaction at acetylenic carbon atom.