Application of a new amidophosphite ligand to Rh-catalyzed asymmetric hydrogenation of ß-dehydroamino acid derivatives in supercritical carbon dioxide: activation effect of protic Co-solvents.

New chiral amidophosphite ligand was synthesized and tested in the Rh-catalyzed asymmetric hydrogenation of (Z)-ß-(acylamino)acrylates in protic solvents and supercritical carbon dioxide (scCO(2) ) The catalytic performance is affected greatly by the acidity of the solvents. Better enantioselectivity (up to 88% ee) was achieved in scCO(2) containing 1,1,1,3,3,3-hexafluoro-2-propanol, compared to neat protic solvents.

(S)-6-Bromo-BINOL-based phosphoramidite ligand with C(1) symmetry for enantioselective hydrogenation and allylic substitution.

(S)-6-Br-BINOL-derived phosphoramidite, a simple monodentate ligand with a stereogenic center at the phosphorus atom, was synthesized for the first time. This stereoselector generated a high level of enantioselectivity (80-95% ee) in the rhodium-catalyzed hydrogenation of alpha-dehydrocarboxylic acid esters and was also successfully employed in the asymmetric palladium-catalyzed allylic substitution of (E)-1,3-diphenylallyl acetate. The optical yield also showed significant dependence with reaction type: up to 70% ee for allylic amination, up to 75% ee for allylic sulfonylation, and up to 90% ee for allylic alkylation.