Transmetal-Catalyzed Enantioselective Cross-Coupling Reaction of Racemic Secondary Benzylic Bromides with Organoaluminum Reagents.

The transmetal-catalyzed enantioselective cross-coupling reaction of secondary benzylic electrophiles with organoaluminum reagents has been developed. The reaction of secondary benzylic electrophiles with alkynylaluminum reagents provides a mild way for the chiral propargyl compounds bearing aromatic group in high yields with good enantioselectivities using NiBr2·diglyme and (R)-iPr-Pybox as the catalytic system. The reaction of secondary benzylic electrophiles with alkenylaluminum reagents affords the corresponding chiral aryl alkenes in moderate yields with excellent stereoselectivities using commercially available PdCl2 and (R)-BINAP as the catalytic system.