[C:1]1([SH:7])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[H-].[Na+].[NH2:10][C:11]1[C:16](Br)=[N:15][C:14]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)=[CH:13][N:12]=1>CN(C=O)C>[NH2:10][C:11]1[C:16]([S:7][C:1]2[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=2)=[N:15][C:14]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)=[CH:13][N:12]=1To a cooled solution of thiophenol (0.10 mL, 1.00 mmol) in dry DMF (10 mL), sodium hydride (NaH) (0.025 g, 1.00 mmol) was added the resulting mixture was stirred for 15 min at 5-10° C. After this time 2-amino-3-bromo-5-phenylpyrazine 17b (0.25 g, 1.00 mmol) was added and the mixture refluxed for 20 h, cooled and extracted with EtOAc. The organic layer was washed with water, dried over Na2SO4, filtered and the solvent removed under reduced pressure to get a crude that was purified by flash chromatography using petroleum ether-EtOAc (60:40 v/v) as eluent, to obtain 0.22 g of the title compound 18b as a brown solid (mp 109-112° C., 79% yield). 1H-NMR (CDCl3): 4.92 (br s, 2H), 7.29-7.50 (m, 8H), 7.74-7.77 (m, 2H), 8.35 (s, 1H). MS (ESI): m/z 280 (M+H1).
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