Synthesis of Tetrasubstituted Olefins by Pd-Catalyzed Addition of Arylboronic Acids to Internal Alkynes

[Reaction: see text] Tetrasubstituted olefins are readily prepared by the Pd-catalyzed cis addition of two aryl groups from an arylboronic acid to opposite ends of the triple bond of internal alkynes. The synthesis proceeds under very mild reaction conditions and tolerates a wide variety of functional groups, including alcohol, aldehyde, ester, TMS, and acetal groups.