A Chiral Chelating Diene as a New Type of Chiral Ligand for Transition Metal Catalysts:  Its Preparation and Use for the Rhodium-Catalyzed Asymmetric 1,4-Addition

As a new type of chiral ligand, a C 2-symmetric norbornadiene derivative (1R,4R)-2,5-dibenzylbicyclo[2.2.1]hepta-2,5-diene (1) was prepared and used for the rhodium-catalyzed asymmetric addition of organoboron and -tin reagents to α,β-unsaturated ketones, which gave high yields of the 1,4-addition products with up to 99% enantioselectivity.