[C:1]1([S:7]([C:10]2[CH:15]=[CH:14][C:13]([CH3:16])=[CH:12][CH:11]=2)(=[O:9])=[O:8])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[OH-:17].[Na+].[O-][Mn](=O)(=O)=O.[K+].[OH2:25]>>[C:1]1([S:7]([C:10]2[CH:11]=[CH:12][C:13]([C:16]([OH:25])=[O:17])=[CH:14][CH:15]=2)(=[O:9])=[O:8])[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1To a suspension of 1-benzenesulfonyl-4-methylbenzene (5.05 g, 21.7 mmol) in H2O (100 mL) were added NaOH (2 pellets) and KMnO4 (6.87 g, 43.5 mmol). The mixture was heated to reflux overnight. The reaction was cooled and additional NaOH (1 pellet) and KMnO4 (4 g, 25 mmol) were added. The reaction was heated to reflux for 20 h. The reaction was cooled to rt and filtered to collect the solids. The filtrate was acidified with conc. HCl. The aqueous suspension was extracted with EtOAc (4×60 mL). The combined organic layers were washed with brine (60 mL), dried (Na2SO4), filtered and concentrated to provide the title compound (1.49 g, 26%) as an ivory powder. 1H NMR (DMSO-d6): δ 8.11 (dd, J=7, 7 Hz, 4H), 7.97 (d, J=7 Hz, 2H), 7.71-7.65 (m, 3H). MS (M−H)− 261.
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