[SH:1][C:2]1[CH:7]=[CH:6][N:5]=[CH:4][CH:3]=1.[F:8][C:9]1[CH:10]=[C:11]([N+:16]([O-])=O)[CH:12]=[CH:13][C:14]=1F.C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C.C(OCC)(=O)C.O>[F:8][C:9]1[CH:10]=[C:11]([CH:12]=[CH:13][C:14]=1[S:1][C:2]1[CH:7]=[CH:6][N:5]=[CH:4][CH:3]=1)[NH2:16]A solution of 4-mercaptopyridine (4.2 g, 35.6 mmol), 3,4-difluoronitrobenzene (5.7 g, 35.7 mmol), and potassium carbonate (12.4 g, 89.7 mmol) in anhydrous DMF (40 mL) was stirred at 40° C. and under argon for 3 h. TLC showed complete reaction. The mixture was diluted with ethyl acetate (100 mL) and water (100 mL) and the aqueous layer was back-extracted with ethylacetate (2×100 mL). The organic layers were washed with a saturated NaCl solution (100 mL), dried (MgSO4), and concentrated under reduced pressure. The crude product was purified by column chromatography with 50% ethyl acetate/50% hexanes. It afforded the desired product as a yellow solid (6.3 g, 71%). TLC (50% EtOAc/50% hexane) Rf 0.53; 1H-NMR (DMSO-d6) δ 7.27 (dd, J=0.76, 4.2 Hz, 2H), 7.78 (dt, J=0.76, 7.2 Hz, 1H), 8.11-8.11 (m, 1H), 8.28-8.33 (m, 1H), 8.5 (dd, J=1.4, 4.6 Hz, 2H), MS [M+H]+=251. Step 2. Preparation of 3-fluoro-4-(4-pyridinylsulfanyl)aniline.
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