Condition optimization^a.

Entry	[Pd]	Ligand	Base	Solvent	Yieldb (%)
1	Pd(OAc)2	PCy3	K2CO3	DCE	45
2	Pd(OAc)2	PCy3	K3PO4	DCE	20
3	Pd(OAc)2	PCy3	NEt3	DCE	Trace
4	Pd(OAc)2	dpppe	K2CO3	DCE	39
5	Pd(OAc)2	PPh3	K2CO3	DCE	26
6	Pd(OAc)2	DPEphos	K2CO3	DCE	60
7	Pd(TFA)2	DPEphos	K2CO3	DCE	42
8	PdCl2	DPEphos	K2CO3	DCE	NR
9	Pd(OAc)2	DPEphos	K2CO3	1,4-Dioxane	Trace
10	Pd(OAc)2	DPEphos	K2CO3	Toluene	Trace
11c	Pd(OAc)2	DPEphos	K2CO3	DCE	63
12c,d	Pd(OAc)2	DPEphos	K2CO3	DCE	73
13 c , d , e	Pd(OAc) 2	DPEphos	K 2 CO 3	DCE	79
14c,d,e,f	Pd(OAc)2	DPEphos	K2CO3	DCE	NR
15c,d,e,g	Pd(OAc)2	DPEphos	K2CO3	DCE	20
16c,d,e,h	Pd(OAc)2	DPEphos	K2CO3	DCE	Trace

^aReaction conditions: 1a (0.2 mmol), 2a (2.0 equiv.), [Pd] (10 mol%), ligand (20 mol%), base (3.0 equiv.) and solvent (2.0 mL) at 120 °C for 12 h under a N₂ atmosphere.

^bIsolated yield.

^cDPEphos (12 mol%).

^d4 Å MS (100 mg) was added.

^eDCE (3.0 mL).

^f2a changed by BrCF₂TMS.

^g2a changed by ClCF₂COOEt.

^hPd(OAc)₂ (5 mol%). NR = no reaction.