For the asymmetric allylation and benzylation reactions, all of the yields of the corresponding products decreased greatly in the absence of Lewis acid ZnCl2, no matter whether the amino acid ester 1a or the formed Schiff base CA-15-1a was employed as donor (Figure ), indicating that the Lewis acid can accelerate the processes of Schiff base formation and deprotonation. Furthermore, the slight decreases in enantioselectivities showed that the Lewis acid can enhance the stereoselective-control ability of the corresponding transition states. It was reasonable to deduce that these reactions took place between the Zn-Schiff base complexes and halohydrocarbons. Therefore, two transition states, TS III and TS IV, were proposed (Figure ). Thus, products (S)-6a and (S)-9a were generated respectively (Figure ).