PGTSA/Ni-catalyzed dehydrogenative heterocoupling of amines^a.

Entry	Catalyst	Cat. (mol%)	Solvent	Temperature (°C)	Time (h)	Base	Yieldb (%)
1	NiCl2	50 mg	Mesitylene	140	24	KOtBu	40
2	CoCl2	50 mg	Mesitylene	140	24	KOtBu	N.R.
3	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	—	60
4	PGTSA/Ni	0.45 mol%	Mesitylene	140	24	KOtBu	72
5	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	KOtBu	93
6	PGTSA/Ni	1.8 mol%	Mesitylene	140	24	KOtBu	93
7	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	KOH	75
8	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	K2CO3	88
9	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	KOtBu	69
10	PGTSA/Ni	0.9 mol%	Toluene	Reflux	24	KOtBu	73
11	PGTSA/Ni	0.9 mol%	EtOH	Reflux	24	KOtBu	40
12	PGTSA/Ni	0.9 mol%	CH3CN	Reflux	24	KOtBu	52
13	PGTSA/Ni	0.9 mol%	Solvent-free	140	24	KOtBu	32
14	PGTSA/Ni	0.9 mol%	Mesitylene	160	24	KOtBu	93
15	PGTSA/Ni	0.9 mol%	Mesitylene	120	24	KOtBu	64
16	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	KOtBu	58c
17	PGTSA/Ni	0.9 mol%	Mesitylene	140	24	KOtBu	89d

^aReaction conditions: 1a (1.0 mmol), 2a (2.0 mmol), and 3 mL of solvent.

^bIsolated yield.

^c1 mmol of aniline was employed.

^dThe reaction was carried out in 10 mmol scale.