The enantioselectivity could be further increased up to 92.5:7.5 e.r. with urea ligand derivatives UL2-UL6, although with lower yields. In addition, corresponding thiourea oxazoline TL1 proved to be ineffective in the catalytic system. Without ligand, only traces of product 3 could be detected, highlighting the unique potential of the ligands in controlling reactivity as well as selectivity (Scheme 3).