C([Li])CCC.Br[C:7]1[CH:12]=[CH:11][C:10]([C:13]([F:16])([F:15])[F:14])=[CH:9][C:8]=1[S:17][CH3:18].[C:19](=[O:21])=[O:20].Cl>CCOCC>[CH3:18][S:17][C:8]1[CH:9]=[C:10]([C:13]([F:16])([F:15])[F:14])[CH:11]=[CH:12][C:7]=1[C:19]([OH:21])=[O:20]
n-Butyllithium (2.5M in hexane, 25 ml) was added under an inert atmosphere to a stirred solution of 4-bromo-3-(methylsulphenyl)benzotrifluoride (16.4 g) in ether maintaining the temperature below -70° C. for 2 hours. The mixture was poured onto solid carbon dioxide pellets, stirred for 10 rains and aqueous hydrochloric acid added. The layers were separated and the aqueous layer was extracted with ether. The combined organic layers were washed with water, dried (MgSO4) and filtered. The filtrate was evaporated and the residue was triturated with cyclohexane and filtered to give 2-(methylsulphenyl)-4-trifluoromethylbenzoic acid (12.4 g) as a white solid NMR (CDCl3 +DMSO-d6): 2.45 (s,3H), 7.2(d,1H), 7.3(s,1H), 8.0(d,1H), 10.7-11(bs,1H).
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