Table 1. Screening of Pd Catalysts and Ligands^a.

entry	Pd (x mol %)/ligand (y mol %)	yield of (E,E)-3a (%)b/ratio of 3a/3a′b
1c	Pd(PPh3)4 (10)/-	41/>99:1
2c,d	Pd(PPh3)4 (10)/-	0/-
3c,e	Pd(PPh3)4 (10)/-	8/-
4	Pd(PPh3)4 (10)/-	58/>99:1
5	Pd(dba)2 (10)/PPh3 (20)	55/>99:1
6	Pd(dba)2 (10)/dppm (10)	0/-
7	Pd(dba)2 (10)/dppe (10)	22/>99:1
8	Pd(dba)2 (10)/dppp (10)	26/>99:1
9	Pd(dba)2 (10)/dppb (10)	62/>99:1
10	Pd(dba)2 (10)/-	0/-
11	Pd(dba)2 (5)/dppb (5)	50/99:1
12	Pd2(dba)3 (5)/dppb (10)	8/-
13	Pd(PPh3)4 (10)/dppb (10)	44/>99:1
14	Pd(OAc)2 (10)/dppb (10)	8/-
15	Pd(TFA)2 (10)/dppb (10)	25/99:1
16f	Pd(dba)2(10)/dppb (10)	87 (81)g/>99:1 (96:4)g

^aUnless specified otherwise, reactions were carried out using 1a (0.1 mmol), 2a (0.3 mmol), NaI (0.3 mmol), and Et₃N (0.3 mmol) in toluene (0.2 M) at 90 °C for 18 h under argon.

^bDetermined by ¹⁹F NMR analysis using benzotrifluoride as the internal standard.

^cAt 80 °C.

^dWithout NaI.

^eWithout Et₃N.

^fConcn = 0.67 M.

^gIsolated yield and ratio in parentheses at 0.2 mmol scale.