[O:1]([C:8]1[CH:14]=[CH:13][C:11](N)=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[S:15](=O)(=O)(O)O.N([O-])=O.[Na+].S[CH2:25][C:26]([OH:28])=O>O.C(=O)([O-])[O-].[Cu+2].C(OCC)(=O)C.CC(C)=O>[O:1]([C:8]1[CH:14]=[CH:13][C:11]([CH2:25][C:26]([OH:28])=[S:15])=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=14-Phenoxyaniline (30 g, 162 mmol) was added in portions to a stirred solution of 98% w/v sulphuric acid (93 ml) in water (480 ml). The mixture was heated at 80° C. for 30 minutes and then cooled to 0°-5° C. A solution of sodium nitrite (13.5 g, 196 mmol) in water (60 ml) was added dropwise and the mixture was stirred for 45 minutes at 0° C. The excess nitrous acid was destroyed with sulphamic acid. The solution was added to a stirred mixture of 2-mercaptoacetic acid (14.7 ml, 211 mmol), basic copper carbonate (10.8 g, 49 mmol) and acetone (180 ml) at 0° C. The mixture was warmed to ambient temperature. After 1 hour ethyl acetate (200 ml) was added and the insoluble material was removed by filtration. The filtrate was extracted with ethyl acetate. The combined extracts were then extracted with a saturated solution of sodium hydrogen carbonate. The combined aqueous extracts were acidified to pH 2 by the addition of 2M hydrochloric acid and extracted with ethyl acetate. The combined extracts were washed with brine and dried (MgSO4). The solvent was removed by evaporation to give 4-phenoxyphenylthioacetic acid as an oil (12.3 g) having a satisfactory NMR spectrum (200 MHz, CDCl3); 3.61 (s,2H), 6.93-7.46 (m,9 aromatic H), after purification by flash chromatography on silica (Merck Kieselgel Art 9385) using ethyl acetate/dichloromethane (1:1 v/v).
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