Table 1. Optimization of reaction conditions ^a .

Entry	Cu salt	Oxidant	Additive (eq.)	Solvent	Yield (%) b
1	Cu(OAc)2		K2CO3 (2)	1,4-Dioxane	0
2	Cu(OAc)2		K2HPO4 (2)	1,4-Dioxane	0
3	Cu(OAc)2		PhCO2Na (2)	1,4-Dioxane	0
4	Cu(OAc)2		Et3N (2)	1,4-Dioxane	<5
5	Cu(OAc)2		Py (2)	1,4-Dioxane	22
6	Cu(OAc)2		2,6-Lutidine (2)	1,4-Dioxane	14
7	Cu(OAc)2		DMAP (2)	1,4-Dioxane	17
8	Cu(OAc)2		TMEDA (1)	1,4-Dioxane	6
9	Cu(OAc)2		2,2′-Dipyridyl (1)	1,4-Dioxane	16
10	Cu(OAc)2		1,10-Phen (1)	1,4-Dioxane	<5
11	CuCl2		Py (2)	1,4-Dioxane	0
12	CuBr2		Py (2)	1,4-Dioxane	0
13	CuOAc		Py (2)	1,4-Dioxane	<5
14	CuBr		Py (2)	1,4-Dioxane	0
15	Cu(OAc)2	Ag2O	Py (2)	1,4-Dioxane	25
16	Cu(OAc)2	TBHP	Py (2)	1,4-Dioxane	10
17	Cu(OAc)2	(tBuO)2	Py (2)	1,4-Dioxane	44
18 c	Cu(OAc)2	(tBuO)2	Py (2)	1,4-Dioxane	59
19 c	Cu(OAc)2	(tBuO)2	Py (2)	DME	46
20 c	Cu(OAc)2	(tBuO)2	Py (2)	THF	40
21 c	Cu(OAc)2	(tBuO)2	Py (2)	Toluene	15
22 c	Cu(OAc)2	(tBuO)2	Py (2)	DME–1,4-dioxane (7 : 3)	84
23 c	Cu(OAc)2	(tBuO)2	Py (1)	DME–1,4-dioxane (7 : 3)	50
24 c	Cu(OAc)2	(tBuO)2	Py (3)	DME–1,4-dioxane (7 : 3)	96 (92)
25 c d	Cu(OAc)2	(tBuO)2	Py (3)	DME–1,4-dioxane (7 : 3)	63
26 c	Cu(OAc)2	(tBuO)2	—	DME–1,4-dioxane (7 : 3)	0

^aReaction conditions: 1a (0.3 mmol), 2a (0.6 mmol), Cu salt (0.3 mmol), oxidant (0.75 mmol), additive, 1.0 mL of solvent, 140 °C, 16 h.

^bYields and conversions are based on 1a, determined by ¹H-NMR using dibromomethane as the internal standard. Isolated yield is in parenthesis.

^cUnder N₂ atmosphere.

^dCu(OAc)₂ (0.15 mmol). Q = 8-quinolinyl.