N([O-])=O.[Na+].N[C:6]1[CH:11]=[CH:10][C:9]([OH:12])=[C:8]([O:13][C:14]([F:17])([F:16])[F:15])[CH:7]=1.[FH:18].N1C=CC=CC=1.O.O.O.[F-].C([N+](CCCC)(CCCC)CCCC)CCC>C(OCC)(=O)C>[F:18][C:6]1[CH:11]=[CH:10][C:9]([OH:12])=[C:8]([O:13][C:14]([F:17])([F:16])[F:15])[CH:7]=133 mg (0.48 mmol) of sodium nitrite was added to a solution of 77 mg (0.4 mmol) of 4-amino-2-trifluoromethoxyphenol in 0.8 mL of 65% (w/w) hydrofluoric acid/pyridine under argon atmosphere with stirring at an outer bath temperature of 0˜5° C. The outer bath was heated to 5˜10° C. and the mixture was stirred for 30 min until the solution turned brownish red. To the above solution were successively added 90 mg (0.4 mmol) of stannous chloride dihydrate and 105 mg (0.4 mmol) of tetrabutylammonium fluoride trihydrate. The solution was slowly heated to—100° C., allowed to react at this temperature for 3.0 h until it was dark brown. The reaction was stopped, naturally cooled, poured into ice water, and 15 mL of ethyl acetate was added. The organic layer was isolated, and the water layer was extracted with 15 mL×2 of ethyl acetate. The organic layers were combined, successively washed with 30 mL of water and 30 mL of saturated saline, dried over anh. MgSO4, filtered and concentrated. The residue was purified by preparative silica gel thin layer chromatography (mobile phase: petroleum ether: ethyl acetate=2:1) to obtain 14 mg of a pale yellow oil. Yield 17.9%.
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