Chloroacetylenes as Michael acceptors. II. Direct ethynylation and vinylation of tertiary enolates.

Abstract

The reaction of ClCCCl, PhCCCl and PhSCCCl with a variety of tertiary enolates leads in 43–90% yields to α-chloroethynyl, α-phenylethynyl and α-thiophenylethynyl derivatives. The −CCCl group is smoothly converted to −CCH using copper powder in HOAc/THF, or is directly reduced (H 2/Lindlar catalyst) to the −CHCH 2 group, thus providing facile access to many α-ethynyl and α-vinyl ketones and esters.