Highly Selective Nickel-Catalyzed Three-Component Coupling of Alkynes with Enones and Alkenyl Boronic Acids: A Novel Route to Substituted 1,3-Dienes

A highly regio- and stereoselective nickel-catalyzed three-component coupling of alkynes with enones and alkenyl boronic acids to afford highly substituted 1,3-dienes is described. The reaction can also be extended to cyclization of enynes with coupling to alkenyl boronic acids. A possible reaction mechanism involving a five-membered nickelacycle as a key intermediate is proposed.