Table 1. Optimization of the Reaction^a.

solvent	catalyst	oxidant	additive	temp (°C)	yield (%)
DCE	Cu(OAc)2 (20 mol %)	I2 (20 mol %)		rt	trace
DCE	Cu(OAc)2	I2		50	42
THF	Cu(OAc)2	I2		50	N.R
DMSO	Cu(OAc)2	I2		50	trace
DMF	Cu(OAc)2	I2		50	N.R
CH3CN	Cu(OAc)2	I2		50	36
DCE	Cu(OAc)2			50	N.R
DCE		I2		50	N.R
DCE		I2	H2O2	50	N.R
toluene	Cu(OAc)2	I2		50	48
toluene	Cu(OTf)2	I2		50	52
toluene	In(OTf)2	I2		50	trace
toluene	Sc(OTf)2	I2		50	N.R
toluene	CuCl2	I2		50	trace
toluene	Cu(BF4)2	I2		50	9
toluene	Cu(OTf)2	I2	BF3·OEt2 (1 equiv)	50	38
toluene	Cu(OTf)2	I2	BF3·OEt2 (20 mol %)	50	trace
toluene	Cu(OTf)2	I2	PTSA (20 mol %)	50	20
toluene	Cu(OTf)2	I2	HCl (20 mol %)	50	50
toluene	Cu(OTf)2	I2		50	48
toluene	Cu(OTf)2	PhI(OAc)2		50	N.R
toluene	Cu(OTf)2	NaI		50	trace
toluene	Cu(OTf)2	KIO3		50	N.R
toluene	Cu(OTf)2	CuI		50	9
toluene	CuI	I2		50	21
toluene	CuBr	I2		50	26
toluene	Cu(OTf)2 (1 equiv)	I2		50	trace
toluene	Cu(OTf)2 (20 mol %)	I2 (1 equiv)		50	31
toluene	Cu(OTf)2 (10 mol %)	I2 (20 mol %)		50	60
toluene	Cu(OTf)2 (5 mol %)	I2 (5 mol %)		50	trace
toluene	Cu(OTf)2(10 mol %)	I2(20 mol %)		60–70	59
toluene	Cu(OTf)2 (10 mol %)	I2 (20 mol %)		80	41
tolueneb	Cu(OTf)2 (10 mol %)	I2 (20 mol %)		60–70	54
toluenec	Cu(OTf)2 (10 mol %)	I2 (20 mol %)		60–70	24
toluened	Cu(OTf)2 (10 mol %)	I2 (20 mol %)		60–70	25

^aReaction conditions: 1a (0.24 mmol), 2a (1.2 mmol), in 2 mL of solvent without inert atmosphere, for 24 h.

^bReaction time: 14 h.

^cIn the presence of argon atmosphere.

^d1a (0.24 mmol), 2a (0.72 mmol).