Expanding the Scope of Atropisomeric Monodentate P-donor Ligands in Asymmetric Catalysis. Hydrogen Transfer Reduction of alfa,beta-unsaturated Acid Derivatives by Rhodium/Ph-BINEPINE Catalysts.

A range of alfa,beta-unsaturated acids and esters have been selectively reduced to the corresponding saturated acid derivatives by hydrogen transfer. As the reducing agent, formic acid was used in the presence of RhI complexes formed with the powerful chiral ligand Ph-binepine (1), an axially chiral binaphthalenetype monodentate P-donor ligand. Very high stereoselectivities (up to 97% ee) were obtained in the case of itaconic acid (2a).