[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([S:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[F:15])=[CH:4][N:3]=1.[OH:16]OS([O-])=O.[K+].C(=O)(O)[O-].[Na+].[OH2:27]>CO>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([S:8]([C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[F:15])(=[O:16])=[O:27])=[CH:4][N:3]=1The product from Step 1 (2.0 g, 8.3 mmol) and OXONE® (7.7 g, 12.5 mmol) were stirred in methanol (50 mL) at room temperature for 6 days. Saturated sodium bicarbonate was added and the suspension stirred for 15 minutes before diluting with water and extracting into ethyl acetate (×2). The combined organic extracts were washed with brine, dried over MgSO4 and concentrated in vacuo while loading onto silica. Dry flash column chromatography using 10–30% ethyl acetate/isohexane gave 2-chloro-5-[(2-fluorophenyl)sulfonyl]pyridine as a white solid (1.95 g, 86%). δH (500 MHz, d6 DMSO): 7.45–7.56 (2H, m), 7.81–7.88 (2H, m), 8.10 (1H, td, J=1.6, 7.6 Hz), 8.37–8.41 (1H, m), 8.98 (1H, d, J=2.6 Hz); m/z (ES+) 272, 274 [MH+].
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