Highly effective and diastereoselective synthesis of axially chiral bis-sulfoxide ligands via oxidative aryl coupling.

A series of axially chiral bis-sulfoxide ligands have been efficiently synthesized via oxidative coupling with high diastereoselectivities. The axial chirality is well controlled by the tert-butylsulfinyl or the p-tolylsulfinyl group. These axially chiral bis-sulfoxides proved to be remarkably efficient ligands for the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to 2-cyclohexenone with 99% ee.