Heterogeneous asymmetric catalysis

Examples of enantioselective catalysts, including homogeneous supported catalysts and biphasic liquid/liquid, are described and compared. In the case of asymmetric hydride transfer, polythiourea was proven to be more efficient for ruthenium-catalyzed reduction of aryl ketones, although the iridium complexes gave rise to higher ee when using amino sulfonamide bound to a polystyrene matrix. In the case of asymmetric reduction, the modification of the binap allows the formation of a polymer that could be used as a catalyst precursor and exhibits enantioselectivities as high as observed in solution, but easier to separate and recycle. Bisoxazoline bound to silica particules could also be used in copper-catalyzed asymmetric Diels-Alder reaction and cyclopropanation with selectivities similar to that obtained in solution.