Stereoselective Synthesis of Trisubstituted Alkenylboranes by Palladium-Catalyzed Reaction of Alkynyltriarylborates with Aryl Halides

摘要

Organoboron compounds are valuable reagents in organic synthesis, especially for carbon-carbon bond forming reactions like Suzuki-Miyaura coupling reaction. In addition, recent studies on boron-containing compounds have demonstrated their potential as functional materials. Therefore, efficient methods to prepare organoboranes in a stereo-defined form are of significant interest. Trisubstituted alkenylboranes can be synthesized by the reaction of alkynyltriorganylborates with electrophiles, like alkyl halides, (π-ally)palladium species, and carbon dioxide. Electrophilic attack at the β-position of the alkynyl group induces 1,2-migration of the organyl group from boron to the α-position. However, an analogous reaction using aryl halides or pseudohalides has not been reported, although such an arylative reaction would significantly reinforce the potential of the 1,2-migration protocol for the synthesis of π-conjugated organic materials. Herein, we report the palladium-catalyzed reaction of alkynyltriarylborates with aryl halides, which affords trisubstituted alkenylboranes in a highly stereoselective manner.