Optimization of the reaction conditions^a.

Entry	Catalyst	Additive	T (°C)	Solvent	Yieldb (%)
1	Rh(cod)2BF4	—	80	Toluene	40
2	Rh(cod)2BF4	—	60	Toluene	60
3	[Rh(cod)Cl] 2	AgBF 4	60	Toluene	85
4	[Rh(cod)Cl]2	AgOTf	60	Toluene	62
5	[Rh(cod)Cl]2	AgNTf2	60	Toluene	—
6	[Rh(cod)Cl]2	AgSbF6	60	Toluene	—
7	[Rh(cod)Cl]2	Sc(OTf)3	60	Toluene	34
8	[Rh(cod)Cl]2	Yb(OTf)3	60	Toluene	32
9	[Rh(cod)Cl]2	In(OTf)3	60	Toluene	28
10	[Rh(cod)Cl]2	NaBArF4	60	Toluene	—
11	[Rh(cod)Cl]2	AgBF4	60	PhCI	60
12	[Rh(cod)Cl]2	AgBF4	60	DCE	78
13	[Rh(cod)Cl]2	AgBF4	60	THE	70
14	[Rh(cod)Cl]2	AgBF4	60	Dioxane	72
15	[Rh(cod)Cl]2	AgBF4	60	MeCN	Trace
16c	[Rh(cod)Cl]2	AgBF4	60	Toluene	86

^aReaction conditions: 1a (0.20 mmol), catalyst (5 mol%), additive (10 mol%), solvent (2 mL), 8 h, Ar. All the reactions were carried out on a 0.20 mmol scale in solvent (2 mL) at 60 °C for 8 h unless otherwise specified.

^bIsolated yield.

^c20 mol% additive was added.