[C:1](=[S:3])=S.[NH2:4][C:5]1[CH:6]=[C:7]([CH:11]=[CH:12][C:13]=1[O:14][CH3:15])[C:8]([OH:10])=[O:9].C(N(CC)CC)C.II.Cl.S([O-])([O-])=O.[Na+].[Na+].C(=O)([O-])O.[Na+]>O.C(OCC)(=O)C.O1CCCC1>[N:4]([C:5]1[CH:6]=[C:7]([CH:11]=[CH:12][C:13]=1[O:14][CH3:15])[C:8]([OH:10])=[O:9])=[C:1]=[S:3]Carbon disulfide (0.26 mL, 4.4 mmol) was added to a mixture comprising 3-amino-4-methoxybenzoic acid (0.25 g, 1.5 mmol), tetrahydrofuran (1.0 mL), water (1.0 mL) and triethylamine (0.51 mL, 3.6 mmol), followed by stirring at room temperature for 6 hours. To the obtained reaction mixture, a tetrahydrofuran (1.0 mL) solution of iodine (0.41 g, 1.6 mmol) was dropwise added over a period of 5 minutes at 0° C., followed by stirring at 0° C. for further 2.5 hours. Thereafter, 1M hydrochloric acid (1.5 mL) and sodium sulfite (38 mg, 0.30 mmol) were added and mixed. Then, ethyl acetate (6 mL) was added, and the organic layer was separated and concentrated under reduced pressure to dryness. To the obtained residue, ethyl acetate (6 mL), water (2 mL), sodium hydrogencarbonate (6 mg, 0.07 mmol) and sodium sulfite (9 mg, 0.07 mmol) were added, the organic layer was separated and concentrated under reduced pressure to dryness to obtain 3-isothiocyanato-4-methoxybenzoic acid as a colorless solid (0.29 g, yield: 94%, HPLC purity: 99%, HPLC retention time: 3.5 min). LC-MS ES-208 (retention time: 21.6 min, condition 3).
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