Chiral phosphine-phosphite ligands containing a stereocenter in the backbone

The behavior of the substituted bisphenol 29 and bisnaphthol 30 derivatives show what influence the biaryl moiety has. Complexes [RhH(CO)2(phosphine-phosphite)] have been used as catalysts in the asymnietric hydroformylation of styrene. 

Styrene Rh= 2000. Ligand to rhodium ratio is 4. T °C = 50. Branched to linear aldehydes ratio. TOP in mol styrene (mol Rh) h determined at the end of the reaction time by GC. Enantiomeric excess. Absolute configuration is given in parentheses. 

The coordination mode of the ligands in the [RhH(CO)2(phosphine-phosphite)] complexes has been studied using IR and NMR spectroscopy under 20 bar of CO/H2. The HP-IR spectrum shows the presence of a single species and HP-NMR spectroscopy shows that the phosphine and the phosphite occupy an apical and equatorial position respectively, as would have been expected from the donor and acceptor properties. This is in contrast with the coordination mode found for the [RhH(CO)2(phosphine-phosphite)] complex of BINAPHOS in which the phosphine occupies an equatorial position and the phosphite an apical position [49]. 

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