First Examples of Improved Catalytic Asymmetric C−C Bond Formation Using the Monodentate Ligand Combination Approach

Using a combination of chiral monodentate phosphoramidite ligands in the rhodium-catalyzed conjugate addition of boronic acids to three different substrates, we have shown for the first time that the ligand combination approach is applicable for C−C bond formation. Chiral catalysts based on hetero-combinations of ligands are found to be more effective than the homo-combinations. ³¹P NMR experiments show that the hetero-combinations are formed in excess over the homo-combinations.