HFIP Mediates a Direct C−C Coupling between Michael Acceptors and Eschenmoser's salt

Abstract

A direct C−C coupling process that merges Michael acceptors and Eschenmoser's salt is presented. Although reminiscent of the Morita–Baylis–Hillman reaction, this process requires no Lewis base catalyst. The underlying mechanism was unveiled by a combination of kinetic, isotopic labelling experiments as well as computational investigations, which showcased the critical role of HFIP as a superior mediator for proton-transfer events as well as the decisive role of the halide counterion.