Rhodium complexes containing chiral P-donor ligands as catalysts for asymmetric hydrogenation in non conventional media

Rhodium-catalysed asymmetric hydrogenation using P-donor ligands, such as new fluorinated (R)-BINOL and azadioxaphosphabicyclo[3.3.0]octane derivatives was carried out in different reaction media such as organic solvent (CH2Cl2), ionic liquid ([BMI][PF6]), supercritical carbon dioxide (scCO(2)) and [BMI][PF6]/scCO(2) mixture. The best enantioselectivities were obtained in neat [BMI][PF6], allowing a recycling up to ten times without activity loss. However, the enantioselectivity was lost due to ligand leaching. The ionic liquid phase containing rhodium molecular species was supported on functionalized multi-walled carbon nanotubes in order to improve the recycling, but unfortunately the asymmetric induction was lost upon catalyst immobilization.