Hydrochloric Acid → 2-Chloro-5-(trifluoromethyl)-1,3-benzothiazole

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3-Amino-4-bromobenzotrifluoride (1.00 g, 4.17 mmol) and potassium ethyl xanthate (1.60 g, 10.0 mmol) were heated to 130° C. in DMF (5 mL) overnight. After cooling to rt, the reaction mixture was diluted with 1 M aqueous HCl (15 mL) and stirred at rt for an additional 30 min. The resulting solid was collected by filtration and washed with water (2×). The solid was dissolved in EtOAc, dried over Na2SO4, filtered, and concentrated under reduced pressure. This gave 0.895 g (91%) of the 2-mercapto intermediate as a yellow solid. LC-MS: RT=8.60 min., [M+H]+=236.2. The material was suspended in sulfuryl chloride (5 mL) and CH2Cl2 (2 mL). After 2 h, water (20 mL) was added and stirring continued for an additional 30 min. The reaction mixture was extracted with EtOAc (3×), and the combined extracts were dried over Na2SO4, filtered, and concentrated under reduced pressure. This gave 0.886 g (98%) of the title compound as an off-white solid. LC-MS: RT=10.12 min., compound does not ionize.

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