Nature Communications

Table 1 Screening of reaction conditions^a.

From: Copper-catalyzed enantioselective Sonogashira-type oxidative cross-coupling of unactivated C(sp³)−H bonds with alkynes


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
19^e	1aa	CuI	Cs₂CO₃	L5	THF	66, 0, 0	94
20^f	1aa	CuI	Cs₂CO₃	L5	THF	31, 0, 0	92
21	1aa	CuI	Cs₂CO₃	–	THF	0, 0, 0	–
22^g	1aa	CuI	Cs₂CO₃	–	THF	0, 0, 0	–
23^g	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

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