High Performance of a Chiral Diene−Rhodium Catalyst for the Asymmetric 1,4-Addition of Arylboroxines to α,β-Unsaturated Ketones

A rhodium complex coordinated with (S,S)-2,5-dibenzylbicyclo[2.2.2]octa-2,5-diene (Bn-bod*) showed high catalytic activity and high enantioselectivity in the asymmetric 1,4-addition of arylboroxines to cyclic α,β-unsaturated ketones, 0.005−0.01 mol % of the catalyst giving high yields of the addition products with not lower than 94% ee. The turnover frequency of the catalyst is up to 1.4 × 104 h-1.