Chiral Phosphine−Olefin Ligands in the Rhodium-Catalyzed Asymmetric 1,4-Addition Reactions

A full overview on the use of chiral phosphine−olefin ligands 1 in the rhodium-catalyzed
asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds is described. Effective
chiral environment of a Rh/1 complex was shown to resemble that of a Rh/(R,R)-Ph-bod* complex by
comparing the experimental results as well as the X-ray crystal structures. High catalytic activity of a Rh/1
complex was disclosed and the catalytic cycle involving a trimer−monomer equilibrium was established
through mechanistic studies using a reaction calorimeter and 31P NMR spectroscopy. A negative nonlinear
effect derived from an inactive trimer−active monomer equilibrium of the catalyst was also successfully
observed.