Table 1. Optimization of the Reaction Conditions^a,^b.

entry	1a/2a (equiv)	[Ir]-Cat(mol %)	[Ni]-Cat (mol %)	TMG (equiv)	yieldc (%)
1	1.5:1.0	1.0	[Ni-1]-Cat (5.0)	1.5	94
2	1.5:1.0	0.15	[Ni-1]-Cat (5.0)	1.5	96
3	1.5:1.0	0.15	[Ni-1]-Cat (1.0)	1.5	95
4	1.5:1.0	0.15	[Ni-2]-Cat (0.20)	1.5	76
5	1.0:1.1	0.15	[Ni-2]-Cat (0.20)	1.5	99
6	1.0:1.1	0.15	[Ni-2]-Cat (0.20)	1.2	99
7	1.0:1.1	0.15	[Ni-2]-Cat (0.20)	1.2	99d

^a[Ir]-Cat = [Ir(ppy)₂(dtbbpy)]PF₆, [Ni-1]-Cat = NiBr₂ + dtbbpy (1.0:0.20 equiv) added separately, [Ni-2]-Cat = preformed [Ni(dtbbpy]Br_2, TMG = 1,1,3,3-tetramethylguanidine,

^bReaction conditions: 1a (0.25 mmol, 1.0 equiv), 2a (0.28 mmol, 1.1 equiv), [Ir]-Cat (0.15 mol %), [Ni-2]-Cat (0.20 mol %), TMG (0.30 mmol, 1.2 equiv), dry and degassed DMSO (0.25 M, 1.0 mL), irradiation at 455 nm for 3 h.

^cYields were determined by GC analysis with naphthalene as internal standard.

^dReaction was up-concentrated to 0.75 M and run for 17 h, and the yield is reported after purification via automated flash-column chromatography.