Enantioselective rhodium-catalysed addition of boronic acids using C2-symmetric aryl diphosphite ligands

The enantioselective rhodium-catalysed conjugate addition of aryl boronic acids to dehydroalanine derivatives has been successfully carried out in the presence of C2-symmetric aryl diphosphite ligand (R,R,R-4) to prepare unnatural amino acid esters. The products have been obtained in up to 72% ee and with good isolated yield.