The Asymmetric Allylation and Benzylation Reactions. Allyl and benzyl chlorides are two other types of commonly used alkylation reagents for carbon-carbon and carbon-heteroatom bonds formations. However, the N-functionalization byproducts can form spontaneously because of their high reactivity. Thus, the chemoselectivity of the chiral aldehydecatalyzed functionalization of N-unprotected amino acid esters with allyl or benzyl chlorides becomes extremely difficult to control. Nevertheless, our initial experimental results revealing that the target allylation product could be obtained in 89% yield with 16% ee under the promotion of a chiral aldehyde-ZnCl2 system encouraged us to pursue high efficiency using allyl or benzyl chlorides. Therefore, we systematically investigated the reaction conditions of the catalytic asymmetric allylation of tert-butyl alaninate 1a with cinnamyl chloride 5a. Chiral aldehyde catalyst screening indicated that most of the 3-formyl BINOL aldehydes could produce 6a in good-to-excellent yields; however, the enantioselectivities were not satisfactory. The 2-formyl BINOL-aldehyde CA-15 gave excellent enantioselectivity (94% ee), but the yield was moderate (61%) (Figure ). We chose CA-15 as the chiral aldehyde catalyst for further condition optimization. Various solvents were evaluated, and mesitylene was optimal in terms of yield and enantioselectivity (Figure , ii). When this reaction was conducted at 50 °C, product 6a was obtained in 65% yield with 94% ee (Figure , iii). We found that the reaction concentration affected the yield to some degree: the usage of 0.4 mL mesitylene at 0.2 mmol scales of reactant 1a could produce compound 6a in 73% yield with 94% ee (Figure , iv). Based on these results, the optimal reaction conditions for the asymmetric allylation reaction were determined. Due to the similar reaction activities of benzyl chlorides with allyl chlorides, we directly applied the above optimal reaction conditions in the asymmetric benzylation reaction. As expected, this reaction took place smoothly, giving the desired product 9a in 54% yield with 90% ee. Then, optimization of the reaction conditions was performed, including the screening of chiral aldehyde catalysts, bases, solvents, and reaction temperature (see Supporting Information, Tables ). Finally, we found that product 9a could be obtained in 71% yield with 91% ee when n-hexane was used as the reaction solvent (Figure ). Thus, the optimal reaction conditions for this asymmetric benzylation were determined. Figure . Substrate scopes of the asymmetric allylation and benzylation reactions.