First examples of improved catalytic asymmetric C-C bond formation using the monodentate ligand combination approach.

[reaction: see text] 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. (31)P NMR experiments show that the hetero-combinations are formed in excess over the homo-combinations.