Asymmetric Henry reaction catalyzed by C2-symmetric tridentate bis(oxazoline) and bis(thiazoline) complexes: Metal-controlled reversal of enantioselectivity

C2-symmetric tridentate bis(oxazoline) and bis(thiazoline) ligands with a diphenylamine backbone are investigated in the catalytic asymmetric Henry reaction of alpha-keto esters with different Lewis acids. The results show that the NH group in C2-symmetric tridentate chiral ligands plays a very important role in controlling both the yields and enantiofacial selectivity of the Henry products.