Table 1. Selected optimization studies ^a .

Entry	Leaving group	Solvent	2a/2′a	% conv. a	% yield b
1	OMs	DME	70 : 30	82	44
2	OP(O)(OEt)2	DME	90 : 10	42	27
3	OTroc	DME	—	n.d.	0
4	OCOC6F5	DME	71 : 29	66	22
5	OSO2Ph	DME	75 : 25	100	61
6	OP(O)(OPh)2	DME	74 : 26	100	58
7	Br	DME	94 : 6	100	77
8 b	Br	DME	89 : 11	100	68
9 c	Br	DME	—	100	0
10	Br	THF	82 : 18	100	63
11	Br	Et2O	—	0	0
12 d	Br	DME	—	0	0

^aAll reactions were performed on 0.5 mmol scale using CuCN (0.5 mmol).

^bThe reaction was run using CuI (0.5 mmol).

^cThe reaction was run using CuSPh (0.5 mmol).

^dThe reaction was performed in the absence of copper(i) salts.