Table 1.

Screening of reaction conditions^a.

Entry	1	[Cu]	Base	L*	Solvent	Yield (%, 3a, 3a′, 3a″)b	Ee (%)c
1	1aa	CuI	Cs2CO3	L1	Dichloromethane (DCM)	–d, 0, 0	–
2	1aa	CuI	Cs2CO3	L2	DCM	–d, 0, 0	–
3	1aa	CuI	Cs2CO3	L3	DCM	<5, 0, 0	6
4	1aa	CuI	Cs2CO3	L4	DCM	8, 0, 0	74
5	1aa	CuI	Cs2CO3	L5	DCM	53, 0, –d	68
6	1aa	CuI	Cs2CO3	L6	DCM	15, 0, 0	51
7	1ab	CuI	Cs2CO3	L5	DCM	–d, 48, 0	–
8	1ac	CuI	Cs2CO3	L5	DCM	0, 0, –d	–
9	1aa	CuI	Cs2CO3	L5	1,2-Dichloroethane	50, 0, –d	76
10	1aa	CuI	Cs2CO3	L5	Benzene	77, 0, 5	64
11	1aa	CuI	Cs2CO3	L5	EtOAc	92, 0, 0	91
12	1aa	CuI	Cs2CO3	L5	THF	88, 0, 0	94
13	1aa	CuBr	Cs2CO3	L5	THF	64, 0, 0	93
14	1aa	CuTc	Cs2CO3	L5	THF	91, 0, 0	92
15	1aa	CuOAc	Cs2CO3	L5	THF	80, 0, 0,	94
16	1aa	CuI	Na2CO3	L5	THF	<5, 0, 81	85
17	1aa	CuI	K2CO3	L5	THF	27, 0, 62	93
18	1aa	CuI	KOtBu	L5	THF	71, 0, 26	93
19e	1aa	CuI	Cs2CO3	L5	THF	66, 0, 0	94
20f	1aa	CuI	Cs2CO3	L5	THF	31, 0, 0	92
21	1aa	CuI	Cs2CO3	–	THF	0, 0, 0	–
22g	1aa	CuI	Cs2CO3	–	THF	0, 0, 0	–
23g	1aa	CuI	Cs2CO3	L5	THF	0, 0, 0	–

^aReaction conditions: 1a (0.1 mmol), 2a (0.2 mmol), [Cu] (10 mol%), L* (10 mol%), and base (0.1 mmol) in dry solvent (1.2 mL) at room temperature (rt) for 16 h

^bYield based on ¹H NMR analysis of the crude product using CH₂Br₂ as an internal standard

^cEe values based on HPLC analysis

^dA trace amount of product

^eCuI (5  mol%), L* (5  mol%) for 24  h

^fCuI (2  mol%), L* (2  mol%) for 36  h

^gWithout 2a