Stereochemistry of addition of mercury salts to alkynes

Abstract

Reactions of Hg(OOCR)2 (R=Et, Prn, Pri, and Bun) with methylphenylacetylene (with the corresponding acids as solvents) give mixtures ofcis- andtrans-adducts. The quantity of thecis-adduct increases with increase in the length of the acyl substituent.syn-Addition also occurs in the acetoxymercuration ofm-chlorophenyl(methyl)acetylene and 1-methoxybut-2-yne; in the latter case, this route predominates. The stereochemistry of the reaction can also depend on the ratio of the reactants. It is proposed that the reaction occurs by several schemes in which these factors manifest themselves in different degrees.