A new reaction of 1-bromoalk-1-ynes; synthesis of 3-alkylalk-1-ynes from terminal acetylenes

Abstract

The reaction of 1-bromoalk-1-ynes with two equivalents of butyl-lithium in hexane gives 3-butylalk-1-ynes; the reactive intermediate is a dilithioalkyne which can also be directly prepared from terminal acetylenes, and selective reaction with alkyl halides in hexane occurs at the propargylic site to provide a general synthesis of 3-alkylalk-1-ynes.