Synthesis
GENERAL METHOD: To a stirred suspension of CuBr (1.57 g, 10.9 mmol) in acetonitrile (25 mL) was added tert-butyl nitrite (tBuONO, 1.63 mL, 13.7 mmol) and the mixture was stirred for 10 min at 60 °C. Subsequently, 2-amino-4-chlorobenzothiazole (1.50 g, 9.13 mmol) was added to the above mixture and the reaction continued to be stirred at 60 °C for 1 hour. After completion of the reaction, the mixture was cooled to room temperature and poured into 1N hydrochloric acid. The resulting precipitate was collected, dissolved in ethyl acetate (EtOAc), washed sequentially with 1N hydrochloric acid and saturated brine, dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane-ethyl acetate (7:1, v/v) as eluent, resulting in 2-bromo-4-chlorobenzothiazole (703 mg, 34% yield) as a brown oil.
References
[1] Chemistry - A European Journal, 2018, vol. 24, # 55, p. 14622 - 14626
[2] Bioorganic and Medicinal Chemistry, 2012, vol. 20, # 3, p. 1201 - 1212
[3] Patent: WO2018/13774, 2018, A1. Location in patent: Page/Page column 685
[4] Organic Letters, 2015, vol. 17, # 15, p. 3722 - 3725
