Table 1. Optimization of the Reaction Conditions^a.

entry	oxidant (equiv)	solvent	yield of 3a (%)b
1	Cu(OAc)2 (1.0)	TCE	73 (61)c
2	–	TCE	0
3	FeCl3 (1.0)	TCE	0
4	MnO2 (1.0)	TCE	0
5	(NH4)2S2O8 (1.0)	TCE	10
6	Cu(EH)2 (1.0)	TCE	69
7	CuCl2 (1.0)	TCE	44
8	Cu(acac)2 (1.0)	TCE	44
9	Cu(OTf)2 (1.0)	TCE	0
10	Cu(OAc)2 (1.0)	1,4-dioxane	2
11	Cu(OAc)2 (1.0)	DMF	20
12	Cu(OAc)2 (1.0)	2-methyl-2-butanol	20
13	Cu(OAc)2 (1.0)	n-PrOH	22
14	Cu(OAc)2 (1.0)	n-BuOH	29
15	Cu(OAc)2 (0.1)/(NH4)2S2O8 (1.0)	TCE	27
16	Cu(OAc)2 (0.1)/air	TCE	47
17	Cu(OAc)2 (0.1)/O2 (1 atm)	TCE	26

^aConditions: 1a (0.8 mmol, 2.0 equiv), 2a (0.4 mmol, 1.0 equiv), oxidant (0.4 mmol, 1.0 equiv, unless otherwise noted), 110 °C, 2 h.

^bIsolated yield.

^cWith 1 mmol of 2a. Abbreviations: TCE, 2,2,2-trichloroethanol; Cu(EH)₂, copper(II) 2-ethylhexanoate; DMF, N,N-dimethylformamide.