[Cl:1][C:2]1[CH:7]=[CH:6][C:5](I)=[CH:4][N:3]=1.[F:9][C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][C:11]=1[SH:16].C(=O)([O-])[O-].[K+].[K+].C(O)CO>[Cu]I.O.C(O)(C)C>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([S:16][C:11]2[CH:12]=[CH:13][CH:14]=[CH:15][C:10]=2[F:9])=[CH:4][N:3]=1
2-chloro-5-iodopyridine (3.0 g, 12.5 mmol), 2-fluorobenzenethiol (1.6 g, 12.5 mmol), potassium carbonate (3.45 g, 25.0 mmol), ethylene glycol (1.55 g, 25.0 mmol) and copper(I) iodide (0.12 g, 0.63 mmol) were stirred in refluxing isopropyl alcohol (50 mL) for 40 hours. Room temperature was attained, water was added and the products extracted 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 isohexane-2% ethyl acetate/isohexane gave 2-chloro-5-[(2-fluorophenyl)thio]pyridine as a pale yellow oil (2.0 g, 67%). δH (500 MHz, d6 DMSO): 7.25–7.29 (1H, m), 7.34–7.39 (1H, m), 7.44–7.51 (2H, m), 7.53 (1H, d, J=8.4 Hz), 7.75 (1H, dd, J=2.6, 8.4 Hz), 8.36 (1H, d, J=2.6 Hz); m/z (ES+) 240, 242 [MH+].
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