BINOL-derived Phosphites Research Articles

Extending the Concept of Mixtures of Chiral Monodentate P-Ligands in Asymmetric Rh- catalyzed Olefin-Hydrogenation: Use of Oxazaphospholidines

The previously described combinatorial concept of using mixtures of monodentate BINOL-derived phosphites, phosphonites or phosphoramidites as superior ligand systems in Rh-catalyzed asymmetric olefin-hydrogenation has been extended to include chiral oxazaphospholidines. Specifically, the latter were prepared from ephedrine and pseudo-ephedrine according to literature procedures. Mixtures of these P-ligands among themselves or in combination with a BINOL-derived phosphonite lead to enhanced enantioselectivity in the Rh-catalyzed hydrogenation of itaconic acid dimethyl ester (ee up to 89%).

Combinatorial approach to the asymmetric hydrogenation of β-acylamino acrylates: use of mixtures of chiral monodentate P-ligands

The previously proposed concept of using mixtures of two different chiral monodentate P-ligands has been extended to the asymmetric Rh-catalyzed hydrogenation of β-acylamino acrylates with formation of chiral β-amino acid derivatives. Mixtures of BINOL-derived phosphites and phosphonites are particularly effective ( ee=94–99% for five different substrates).