Optimization of the reaction conditions^a.

Entry	Cu	Ligand	Base	Solvent	Yieldb (%)
1	IMesCuCl	PPh3	LiOtBu	Toluene	58
2	IPrCuCl	PPh3	LiOtBu	Toluene	26
3	CuBr	PPh3	LiOtBu	Toluene	No reaction
4	IMesCuCl	—	LiOtBu	Toluene	Trace
5	IMesCuCl	BINAP	LiOtBu	Toluene	67
6	IMesCuCl	PCy3	LiOtBu	Toluene	29
7c	IMesCuCl	BINAP	LiOtBu	Toluene	57
8d	IMesCuCl	BINAP	LiOtBu	Toluene	69
9d	IMesCuCl	BINAP	KOtBu	Toluene	58
10d	IMesCuCl	BINAP	NaOMe	Toluene	42
11d,e	IMesCuCl	BINAP	LiOtBu	Toluene	89
12d,e	IMesCuCl	BINAP	LiOtBu	PhCl	76
13d,e	IMesCuCl	BINAP	LiOtBu	MeCN	43
14 d , e , f	IMesCuCl	BINAP	LiO t Bu	Toluene	91

^aReaction conditions: 1a (0.1 mmol), B₂pin₂ (0.15 mmol), 2a (0.15 mmol), catalyst (5 mol%), ligand (10 mol% for monodentate ligand, 5 mol% for bidentate ligand), base (1.5 equiv.), solvent (1 mL), 90 °C, 12 h.

^bIsolated yields.

^cBINAP (2.5 mol%).

^dBINAP (7.5 mol%).

^e2a (0.35 mmol).

^f100 °C.