Stereodefined Construction of Trisubstituted Alkenes by Direct Coupling Reaction of Allylating Agents, Alkynes, and Organoboranes

Tandem reaction : The Pd‐catalyzed three‐component coupling reaction of an allylic alcohol, terminal alkyne, and organoborane to give ( E )‐1‐substituted 2‐alkyl‐1,4‐pentadienes, involving geminal allylation and alkylation at the acetylenic terminal carbon, is described. Bis‐diene undergoes a similar multicomponent coupling reaction with acetylene and organoborane, involving cyclization of bis‐π‐allylpalladium, to form trans ‐allyl pentadienyl cyclic and heterocyclic compounds with excellent regio‐ and stereoselectivities (see scheme).