Study of reaction conditions^a.

Entry	Variation from standard conditions	Yield of 3aa (%)
1	None	73, 70b
2	Without CuCl2	<10
3	CuI instead of CuCl2	38
4	Cu(OAc)2 instead of CuCl2	27
5	CuBr2 instead of CuCl2	53
6	FeCl3 instead of CuCl2	55
7	nBu4NI instead of KI	72
8	NaI instead of KI	64
9	I2 instead of KI	45
10	Without KI	<10
11	Under argon	60
12	DMF instead of DMSO	25
13	1,4-Dioxane instead of DMSO	30
14	Toluene instead of DMSO	31

^aReaction conditions: 1a (0.1 mmol), 2a (0.05 mmol), CuCl₂ (0.03 mmol), KI (0.05 mmol), DMSO (1 mL), 120 °C, 24 h, under air. Isolated yields.

^b5 mmol scale.