Table 2. Reaction condition optimization^a.

Entry	Temp. (°C)	Oxidation reagents	Loading of oxidation reagents (eq.)	Solventsb	Loading of CuI/Bent-NH2 (mg mmol−1)	Time (h)	Isolated yieldc (%)
1	RT	K2S2O8	1	DMSO	40	8	3
2	60	K2S2O8	1	DMSO	40	8	6
3	80	K2S2O8	1	DMSO	40	8	16
4	100	K2S2O8	1	DMSO	40	8	18
5	120	K2S2O8	1	DMSO	40	8	19
6	100	K2S2O8	0	DMSO	40	8	NRd
7	100	K2S2O8	2	DMSO	40	8	32
8	100	K2S2O8	3	DMSO	40	8	NRd
9	100	TBHP	2	DMSO	40	8	17
10	100	K2S2O8	2	Sulfolane	40	8	5
11	100	K2S2O8	2	DMFe	40	8	11
12	100	K2S2O8	2	ACNe	40	8	28
13	100	K2S2O8	2	None	40	8	NRd
14	100	K2S2O8	2	DMSO	0	8	18
15	100	K2S2O8	2	DMSO	10	8	27
16	100	K2S2O8	2	DMSO	20	8	31
17	100	K2S2O8	2	DMSO	60	8	30
18	100	K2S2O8	2	DMSO	40	1	26
19	100	K2S2O8	2	DMSO	40	2	27
20	100	K2S2O8	2	DMSO	40	3	29
21	100	K2S2O8	2	DMSO	40	4	30
22	100	K 2 S 2 O 8	2	DMSO	40	5	32
23	100	K2S2O8	2	DMSO	40	6	31
24	100	K2S2O8	2	DMSO	40	7	32
25	100	K2S2O8	2	H2O	40	5	8
26	100	K2S2O8	2	EtOH	40	5	NRd

^aReaction conditions: hydrazone (1 mmol), oxidation reagents (1–3 eq.), solvents (1 mL), CuI/Bent-NH₂ (0–60 mg mmol⁻¹).

^bVolume of solvent: 1 mL.

^cIsolated yield was recorded by column chromatography with n-hexane : ethyl acetate = 98 : 2.

^dNR = No reaction.

^eDMF = Dimethylformamide, ACN = Acetonitrile.