Regioselective Propargylation of Carbonyl Compounds with (3-Bromoprop-1-ynyl)trimethylsilane Promoted by Reactive Barium

A Barbier-type propargylation of aldehydes with (3-bromoprop-1-ynyl)trimethylsilane has been achieved using reactive barium as a low-valent metal in THF. This process is effective also for obtaining the desired homopropargylic alcohols in high yields from the corresponding ketones including enolizable ketones such as cyclopent-2-enone.