Table 1. Optimization of the Reaction Conditions^a.

entry	Cu catalyst	ligand	x	yield (%)b
1	Cu(OAc)2	none	1.0	68
2	Cu(OAc)2·2H2O	none	1.0	69
3	Cu(OTf)2	none	1.0	55
4	CuCl	none	1.0	10
5	CuTc	none	1.0	16
6	Cu powder	none	1.0	<5
7	Cu(CH3CN)4BF4	none	1.0	10
8	Pd(OAc)2	none	1.0	<5
9	Cu(OAc)2·2H2O	2,2′-bpy	1.0	18
10	Cu(OAc)2·2H2O	1,10-phen	1.0	<5
11	Cu(OAc)2·2H2O	tpy	1.0	<5
12	Cu(OAc)2·2H2O	4,4′-bpy	1.0	92
13	Cu(OAc)2·2H2O	4,4′-bpy	0.1	45
14	Cu(OAc)2·2H2O	4,4′-bpy	0.3	90
15c	Cu(OAc)2·2H2O	4,4′-bpy	0.3	23
16d	Cu(OAc)2·2H2O	4,4′-bpy	0.3	0

^aConditions: substrate 1a (0.3 mmol), Cu catalyst (10 mol %), ligand (10 mol %), B₂pin₂ (1.0 equiv), MeOH (2.0 mL) under a N₂ atmosphere at 60 °C for 18 h.

^bYields determined by ¹H NMR with CH₂Br₂ as internal standard.

^cEtOH instead of MeOH.

^dH₂O instead of MeOH.