Table 1.

Optimization of Cu/nitroxyl catalyzed aerobic oxidation of primary amine to nitrile.^a

entry	Cu	ligand	nitroxyl	base	yield (%)b
					2a	3a
1	CuOTf	bpy	TEMPO	NMI	25	50
2	CuI	bpy	TEMPO	NMI	27	34
3	CuI	bpy	ABNO	NMI	78	22
4	CuI	bpy	AZADO	NMI	77	23
5	CuI	bpy	ketoABNO	NMI	53	46
6	CuI	4,4′-tBu2bpy	ABNO	NMI	87	13
7	CuI	4,4′-Me2bpy	ABNO	NMI	80	14
8	CuI	4,4′-OMe2bpy	ABNO	NMI	74	26
9	CuI	4,4′-tBu2bpy	ABNO	DMAP	90	4
10c	CuI	4,4′-tBu2bpy	ABNO	DMAP	75	24

^aConditions: 1a (0.5 mmol), Cu, ligand, nitroxyl, and base in CH₃CN (2.0 mL) under O₂ balloon at room temperature for 15 h.

^bYield determined by ¹H NMR (internal standard: 1,1,2,2-tetrachloroethane).

^cCarried out under air.