N([O-])=[O:2].[Na+].[CH2:5]([O:12][C:13]1[C:14]([CH3:21])=[CH:15][C:16]([F:20])=[C:17]([CH:19]=1)N)[C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1>O.C(O)(=O)C.S(=O)(=O)(O)O.O.O.O.[N+]([O-])([O-])=O.[Cu+2].[N+]([O-])([O-])=O.[Cu]=O>[CH2:5]([O:12][C:13]1[C:14]([CH3:21])=[CH:15][C:16]([F:20])=[C:17]([OH:2])[CH:19]=1)[C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1A solution of sodium nitrite (1.68 g, 24 mmol) in water (3.5 ml) was added to a solution of 5-benzyloxy-2-fluoro-4-methylaniline (4.7 g, 20 mmol) in acetic acid (25 ml) and 70% sulphuric acid (25 ml) at 10° C. The mixture was stirred at 10° C. for 20 minutes and a solution of copper(II)nitrate trihydrate (481 g, 2 mol) in water (790 ml) followed by copper(II)oxide (3 g, 19 mmol) was added. The mixture was stirred for 3 hours then extracted with ethyl acetate. The organic layer was washed with water, brine, dried (MgSO4) and the solvent removed by evaporation. The residue was purified by column chromatography eluting with petroleum ether/ether (85/15) to give 5-benzyloxy-2-fluoro-4-methylphenol (1.25 g, 27%) as an orange oil.
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