[NH:1]([C:5]1[CH:13]=[CH:12][C:8]([C:9]([OH:11])=[O:10])=[CH:7][N:6]=1)[C:2]([NH2:4])=[S:3].Br[CH:15]([CH:18]=O)[CH:16]=[O:17].C([O-])(=O)C.[Na+]>C(O)(=O)C.O>[CH:16]([C:15]1[S:3][C:2]([NH:1][C:5]2[CH:13]=[CH:12][C:8]([C:9]([OH:11])=[O:10])=[CH:7][N:6]=2)=[N:4][CH:18]=1)=[O:17]A mixture of 6-thioureido-nicotinic acid (197 mg, 1 mmol), 2-bromomalonaldehyde (166 mg, 1.1 mmol) and sodium acetate (100 mg) in acetic acid (2 mL) was stirred at 100° C. for 20 min. The mixture was then cooled to RT, diluted with water and the precipitates were collected. The solid was washed with water, then methanol and dried in vacuo to afford 6-(5-formyl-thiazol-2-ylamino)-nicotinic acid, (240 mg, 96%). MS m/z 250 (M+H)+. 1H NMR (DMSO-d6) δ 12.7 (s, 1 H), 9.12 (s, 1 H), 8.92 (s, 1 H), 8.38 (s, 1 H), 8.24 (d, 1 H, J=5.6 Hz), 7.21 (d, 1 H, J=5.6 Hz). 13C NMR (DMSO-d6) δ 183.5, 166.0, 165.1, 153.3, 151.5, 148.8, 139.1, 131.2, 120.3, 110.0.
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