High performance of a chiral diene-rhodium catalyst for the asymmetric 1,4-addition of arylboroxines to alpha,beta-unsaturated ketones

reaction: see text] A rhodium complex coordinated with (S,S)-2,5-dibenzylbicyclo2.2.2]octa-2,5-diene (Bn-bod) showed high catalytic activity and high enantioselectivity in the asymmetric 1,4-addition of arylboroxines to cyclic alpha,beta-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 x 10(4) h(-1).