Reaction optimization^a.

Entry	Photocatalyst	Solvent	T (°C)	Yieldb (%)
1	fac-Ir(ppy)3	THF	rt	26
2	fac-Ir(ppy)3	DMSO	rt	2
3	fac-Ir(ppy)3	MeCN	rt	56
4	Ru(bpy)3Cl2·6H2O	MeCN	rt	69
5	Na2Eosin Y	MeCN	rt	69
6c	Na2Eosin Y	MeCN	rt	70
7c	None	MeCN	rt	45
8c	None	MeCN	0	78
9c	None	MeCN	−20	88 (85)
10c,d	None	MeCN	−20	2

^aReaction conditions: 1a (0.20 mmol), ⁿBuLi (0.22 mmol), in Et₂O (2 mL), 0 °C to rt, 1 h, under Ar. After vinylboron ate complex formation, solvent exchange to the selected solvent (2 mL) was performed.

^bGC yield using n-C₁₄H₃₀ as an internal standard; yield of isolated product is given in parentheses.

^c4 mL MeCN was used.

^dReaction carried out in the dark.