Table 1 Optimization of reaction conditions^a


Entry	Deviation from standard conditions	Yield of 4 (%)^b
1	None	91^c
2	(4-BrC₆H₄)₃N (3a) as the catalyst	5 (65)
3	(4-MeO₂CC₆H₄)₃N (3b) as the catalyst	44 (38)
4	3c as the catalyst	38 (25)
5	No 3	58^d (7)
6	Reaction at RT	63
7	2 equiv of 2	28^e
8	No ⁱPrCO₂H	60
9	AcOH as the acid	77
10	EtCO₂H as the acid	87
11	CF₃CO₂H as the acid	78
12	TsOH•H₂O as the acid	80
13	Pt plate (1 cm × 1 cm) as anode	87
14	Graphite plate (1 cm × 1 cm) as anode	66

^aReaction conditions: reticulated vitreous carbon (RVC) anode (1 cm × 1 cm × 1.2 cm), Pt plate cathode (1 cm × 1 cm), 1 (0.2 mmol), 2 (0.5 mL, 9 mmol), MeCN (5.5 mL), Et₄NPF₆ (0.2 mmol), 12.5 mA (j_anode = 0.16 mA cm⁻²), 1.6 h
^bDetermined by ¹H NMR analysis using 1,3,5-trimethoxybenzene as the internal standard. Unreacted 1 in parenthesis
^cYield of isolated 4
^d16% of 5 and 6% of 6
^e8% of 5

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