Table 1. Optimization studies for 1,2-bis(trifluoromethylation) of aryne precursor 1a ^a .

Entry	Oxidant	Solvent	Temp. (°C)	Yield b (%)
1 c	Air	DMF	50	30
2	None	DMF	50	0
3	BQ	DMF	50	4
4	Cu(OAc)2	DMF	50	7
5	AgOAc	DMF	50	26
6	PhI(OAc)2	DMF	50	26
7	DDQ	DMF	50	58
8 d	DDQ	DMF/DMSO	50	77
9 d	DDQ	DMF/DMSO	rt	78
10 e	DDQ	DMF/DMSO	rt	62
11 f	DDQ	DMF/DMSO	rt	77

^aUnless specified otherwise, reactions were carried out using 1a (0.1 mmol), [CuCF₃] (0.4 mmol in 1.0 mL DMF), oxidant (0.2 mmol) and DMF (1.0 mL), under argon.

^bDetermined by ¹⁹F NMR analysis using benzotrifluoride as the internal standard.

^cReaction was open to air.

^dDMF : DMSO = 1.0 : 1.0 mL.

^eDMF : DMSO = 1.0 : 0.5 mL.

^fDMF : DMSO = 1.0 : 2.0 mL.