Optimization of conditions for imine using CH₃CN.^a,b.

Entry	[Acid/base]	[Cu(X)n]	[Cu quant.]	Yield 2ab (%)	Yield 3ab (%)
1	HOAc	Cu(OAc)2	20 mol%	10	11
2	HCO2H	Cu(OAc)2	20 mol%	10	36
3	t-BuOH	Cu(OAc)2	20 mol%	46	51
4	i-PrOH	Cu(OAc)2	20 mol%	39	55
5	HCl	Cu(OAc)2	20 mol%	0	n.d
6	KOtBu	Cu(OAc)2	20 mol%	51	60
7	NaOtBu	Cu(OAc)2	20 mol%	41	53
8	LiOtBu	Cu(OAc)2	20 mol%	25	40
9	Cs2CO3	Cu(OAc)2	20 mol%	28	49
10	None	Cu(OAc) 2	20 mol%	98	>99
11	None	Cu(OTf)2	20 mol%	31	47
12	None	Cu(ClO4)2	20 mol%	59	71
13	None	Cu(C2H5O2)2	20 mol%	68	79
14	None	CuCl2	20 mol%	79	81
15	None	CuI	20 mol%	63	88
16	None	CuBr	20 mol%	58	80
17	None	CuCl	20 mol%	46	59
18	None	Cu(OAc)2	5 mol%	62	74
19	None	Cu(OAc)2	10 mol%	75	83
20	None	Cu(OAc)2	15 mol%	88	91
21	None	Cu(OAc)2	25 mol%	97	99
22	None	Cu(OAc)2	30 mol%	98	99

^aConditions: 1a (0.2 mmol), Cu(X)_n (Cu-catalysts), acid/base (1.0 eq.), N₂, 135 °C, CH₃CN (1.2 mL), 24 h.

^bIsolated yield. n.d; not determined.