Rhodium-Catalyzed Asymmetric Construction of Quaternary Carbon Stereocenters:  Ligand-Dependent Regiocontrol in the 1,4-Addition to Substituted Maleimides

A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to substituted maleimides has been described. The regioselectivity in this reaction is controlled by the choice of ligand (dienes or bisphosphines), and 1,4-adducts with a quaternary stereocenter can be obtained with high regio- and enantioselectivity by the use of (R)-H8-binap.