Synthesis
General procedure for the synthesis of 5-fluoro-2-aminobenzothiazole from 1-(3-fluorophenyl)-2-thiourea: 1-(3-fluorophenyl)-2-thiourea (270 mg, 1.59 mmol) was dissolved in dichloromethane (3 mL) at 0 °C. A solution of bromine (279 mg, 1.74 mmol) in dichloromethane (1 mL) was slowly added dropwise for 30 min at 10 °C or lower. Subsequently, the reaction mixture was refluxed for 3 hours. After completion of the reaction, the organic layer was dried with anhydrous magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography (eluent: dichloromethane/petroleum ether = 1:1) and dried with anhydrous magnesium sulfate to give the final 5-fluoro-2-aminobenzothiazole (183 mg, 68% yield).
References
[1] Patent: KR101659952, 2016, B1. Location in patent: Paragraph 0247; 0248; 0252
[2] Bioorganic and Medicinal Chemistry, 2006, vol. 14, # 24, p. 8599 - 8607
[3] Journal of the Chemical Society [Section] C: Organic, 1969, p. 268 - 272
[4] Patent: US5356864, 1994, A
[5] Patent: WO2013/163244, 2013, A1. Location in patent: Paragraph 00212
