Table 1.

Optimization of the reaction conditions^a

entry	solvent	reoxidant	additive	temp (°C)	3a (%)b
1	tBuOH	Cu(OAc)2	--	80	55
2	DMSO	Cu(OAc)2	--	80	53
3	DMA	Cu(OAc)2	--	80	70
4	DMF	Cu(OAc)2	--	80	78
5	DMF	CuCl2	--	80	0
6	DMF	AgOAc	--	80	43
7	DMF	PhCO3tBuc	--	80	59
8	DMF	Cu(OAc)2	LiBF4	80	80
9	DMF	Cu(OAc)2	BiCl3	80	39
10	DMF	Cu(OAc)2	CsOAc	80	77
11	DMF	Cu(OAc)2	K2CO3	80	68
12	DMF	Cu(OAc)2	KTFA	80	85
13	DMF	Cu(OAc)2	KTFA	50	73
14	DMF	Cu(OAc)2	KTFA	110	69
15	DMF	Cu(OAc)2	KTFA	80	87d

^aReaction conditions unless otherwise specified: 1 (0.2 M), 2a (2 equiv), Pd(OAc)₂ (10 mol %), reoxidant (2 equiv), additive (1 equiv) under N₂ at 80 °C in 24 h. (PMP=para-methoxyphenyl)

^b1H NMR yield vs. Ph₃SiMe (1 equiv) as the internal standard.

^c1 equiv.

^dCompleted in 3 h. (Detailed optimization is available in the Supporting Information.)