Table 1.

Optimization of the reaction conditions.^a

entry	Ni salt (ligand)	activator	solvent	yield (%)b
1	NiBr2(dtbbpy)	A1	DMAc	50
2	NiBr2(dtbbpy)	A2	DMAc	0
3	NiBr2(dtbbpy)	A3	DMAc	56
4	NiBr2(dtbbpy)	A4	DMAc	0
5	NiBr2(dtbbpy)	A5	DMAc	0
6c	NiBr2(dtbbpy)	A3	DMAc	74
7d	NiBr2(dtbbpy)	A3	DMAc	68
8c	NiCl2(dtbbpy)	A3	DMAc	37
9c	NiBr2(bpy)	A3	DMAc	67
10c	NiBr2(phen)	A3	DMAc	8
11c	NiBr2diglyme/4,4-dCO2Me-bpy	A3	DMAc	61
12c	NiBr2diglyme/4,4-dMeO-bpy	A3	DMAc	65
13c	NiBr2(dtbbpy)	A3	NMP	53
14c	NiBr2(dtbbpy)	A3	DMF	trace

^aReaction conditions: 1a (0.1 mmol), 2 (0.15 mmol), Ni catalyst (0.01 mmol), Hantzsch ester (0.15 mmol), solvent (1.0 mL), activator (0.15 mmol), purple LEDs, 7 h. ^bYields determined by ¹⁹F NMR spectroscopy using trifluoromethoxybenzene as an internal standard. ^cAdding 3.0 equiv H₂O. ^dAdding 10.0 equiv H₂O.