Table 1. Optimization of the Reaction Conditions with Acrolein^a.

entry	catalytic mixb	solvent	time	temp	GC–MS responsec	ratio 4a:5j
1	7a/8a/9	DMF	24 h	rt	80	1:2
2	7a/8a/9	MeCN	24 h	rt	85	1:2
3	7a/8a/9	ethanol	24 h	rt	<1	1:2
4	7b/8a/9	MeCN	24 h	rt	77	1:2
5	7a/8b/9	MeCN	24 h	rt	<1	1:2
6	7a/8a/air	MeCN	24 h	rt	81	1:2
7	7a/8a/9	MeCN	0.5 h	100 °C	65	1:2
8	7a/8a/9	MeCN	24 h	rt	66	2:1
9	7a/8a/9	MeCN	24 h	rt	60	5:1

^aAll reactions were carried out with acrolein (4a) and p-tolylboronic acid (5j), on a 1 mmol scale with Pd(II) catalyst (0.02 mmol), ligand (0.024 mmol), reoxidant (p-bzq, 1 mmol or air), and solvent (2 mL) for the time and temperature indicated.

^bCombination of Pd(II) catalyst, ligand, and reoxidant, consisting of either Pd(OAc)₂ (7a) or Pd(OCOCF₃)₂ (7b), dmphen (8a) or dppp (8b), and p-bzq (9) or air as indicated.

^cNaphthalene was added to each reaction and the GC–MS response was calculated according to (peak area of 6j/naphthalene peak area) × (c_naphthalene/c_4a or 5j) × 100. The amount of homocoupled product was <5%. No double arylated Heck product was detected.