Table 1. Reaction Conditions Optimization^a.

entry	change from the standard conditions	yield (%)b
1	none	76
2	NiCl2(PPh3)2 instead of Ni(acac)2	trace
3	Ni(cod)2 instead of Ni(acac)2	40
4	NiCl2[P(CH3)3]2 instead of Ni(acac)2	28
5	Ni(dppf)Cl2 instead of Ni(acac)2	trace
6	Ni(PPh3)4 instead of Ni(acac)2	trace
7	NiCl2 instead of Ni(acac)2	trace
8	254 nm UV instead of blue LED	trace
9	365 nm UV instead of blue LED	trace
10	filament lamp instead of blue LED	trace
11	DMSO instead of DMF	no reaction
12	o-xylene instead of DMF	29
13	THF instead of DMF	50
14	dioxane instead of DMF	trace
15	EtOAc instead of DMF	16
16	DCE instead of DMF	trace
17	air instead of SeO2	49
18	CuCl2 instead of SeO2
19	Cu(OAc)2 instead of SeO2	20
20	BQ instead of SeO2
21	MnO2 instead of SeO2
22	m-CPBA instead of SeO2
23	BPO instead of SeO2	15
24	t-BuOOH instead of SeO2
25	AgOAc instead of SeO2	30

^aYnone 1a (0.2 mmol, 1.0 equiv) and catalyst (0.02 mmol, 10 mol %) in solvent (2 mL) under irradiation using light source with oxidant (0.3 mmol, 1.5 equiv) at room temperature for 5 h.

^bIsolated yield.