Screening of the reaction conditions^a.

Entry	Catalyst	Solvent	Current (mA)	Time (h)	Yieldb (%)
1	DTBP	CH3CN/H2O	30	5	Trace
2	(NH4)2S2O8	CH3CN/H2O	30	5	34
3	Na2S2O8	CH3CN/H2O	30	5	49
4	K 2 S 2 O 8	CH 3 CN/H 2 O	30	5	94
5	K2S2O8	t-BuOH/H2O	30	5	39
6	K2S2O8	DMSO/H2O	30	5	58
7	K2S2O8	DMF/H2O	30	5	Trace
8	K2S2O8	H2O	30	5	29
9	K2S2O8	CH3CN/H2O	30	6	93
10	K2S2O8	CH3CN/H2O	30	4	65
11	K2S2O8	CH3CN/H2O	40	5	86
12	K2S2O8	CH3CN/H2O	20	5	64
13	K2S2O8	CH3CN/H2O	—	5	Trace
14	—	CH3CN/H2O	30	5	Trace
15c	K2S2O8	CH3CN/H2O	30	5	82
16d	K2S2O8	CH3CN/H2O	30	5	67

^aReaction condition: undivided cell, Pt anode, Pt cathode, 1a (0.5 mmol), 2a (0.6 mmol), oxidant (0.6 mmol) and CH₃CN/H₂O (v/v = 2 : 1, 3 mL), under air at room temperature.

^bYields were determined by HPLC.

^cPt(+)/C(−) instead of Pt(+)/Pt(−).

^dC(+)/Pt(−) instead of Pt(+)/Pt(−).