Mechanistic studies of the palladium(II)–copper(II)-mediated demercuriation of cycloalkyl and cycloalkylmethyl systems

Abstract

The likely events involved in the conversion of cyclohexylmethylmercuric chloride into predominantly trans-4-methylcyclohexyl chloride, on treatment with PdCl₂–CuCl₂ in acetic acid, have been identified by product and deuterium-labelling studies, as well as by the behaviour of probable intermediates. Extension to related cycloalkyl- and cycloalkylmethyl-mercuric chlorides is reported, and mechanistic changes occur as a function of ring size, with elimination–re-addition of [HPdX] being important in cyclohexyl systems, but carbocation formation dominating in cyclooctyl cases.