Table 1. Optimization of reaction conditions^a.

	Metal salt	Ligand	Add.	Yield	Ee/%
1	Mg(OTf)2	L3-PiPr3	—	15	14
2	MgCl2	L3-PiPr3	—	12	15
3	Ni(OTf)2	L3-PiPr3	—	13	11
4	Y(OTf)3	L3-PiPr3	—	26	53
4	La(OTf)3	L3-PiPr3	—	18	49
5	Sc(OTf)3	L3-PiPr3	—	27	91
6	Sc(OTf)3	L3-PrPr3	—	26	73
8	Sc(OTf)3	L3-RaPr3	—	22	8
9	Sc(OTf)3	L3-PiPr2	—	22	55
10b	Sc(OTf)3	L3-PiPr3	—	42	92
11b	Sc(OTf)3	L3-PiPr3	MgCl2	63	92

^aThe reactions were performed with metal salt/ligand (1 : 1, 10 mol%), 1a (0.2 mmol), and 2a (0.1 mmol), in 1,2-dichloroethane (1.0 mL) at 60 °C for 36 h. Isolated yield. The ee was determined by UPCC analysis on a chiral stationary phase.

^b1,1,2,2-Tetrachloroethane (1.0 mL) as the solvent, 1a (2.2 equiv.).