Chiral bidentate (phosphinophenyl)benzoxazine ligands in asymmetric catalysis

The new chiral bidentate (phosphinoaryl)benzoxazine ligands 2 were applied in asymmetric catalysis. Rhodium and copper complexes catalyzed the hydrosi lylation of acetophenone and [4 + 2] cycloadditions with moderate enantiose lectivity. Iridium complexes were used to hyrogenate di, tri-, and tetrasub stituted alkenes, giving products with moderate to high enantiomer excesses . Enantioselective allylic substitution and Heck reactions catalyzed by [(p hosphinoaryl)benzoxazine)palladium complexes occurred with high enantiosele ctivities. The results were similar to those obtained with the correspondin g dihydro(phosphinoaryl)oxazole ligands. Comparison of the structures of (d iphenylallyl)(benzoxazine)palladium and (diphenylallyl)(dihydrooxazole)pall adium complexes showed that the coordination geometries and the chiral envi ronments of the metal centers are very similar, which explains why the enan tioselectivities induced by the two ligand classes are in the same range.