Table 1. Optimization of reaction conditions.

Entry	Cu catal.	Organocatal.	Additive	Yield (%)*	ee %†
1	CuOTf	C1	–	(84)‡	–
2	CuOTf	C2	–	(76)§	–
3	CuOTf	A1	–	47	63
4	CuOTf	A1	P1	52	91||
5	CuOTf	A2	P1	52	76||
6	CuOTf	A3	P1	74	84||
7	CuOTf	A4	P1	65	93||
8	CuOTf	A5	P1	73	89||
9	CuOTf	A6	P1	53	87||
10	CuOTf	A4	P2	31	73||
11	CuOTf	A4	P3	81	73||
12	CuOTf	A4	P4	67	63||
13	CuOTf	A4	P1	76	93
14	(CuOTf)2•toluene	A4	P1	78	93
15	(CuOTf)2	A4	P1	70	92
16	(CuOTf)4PF6	A4	P1	77	93
17	CUBr	A4	P1	(87)¶	–

*Determined by GC using n-dodecane as an internal standard.

†Determined by chiral high-performance liquid chromatography.

‡The imine intermediate obtained in 84% yield.

§The imine intermediate obtained in 76% yield.

||Twenty mole percent of additive was used.

¶The imine intermediate obtained in 87% yield.