Carbon Disulfide → 5-Chloro-2-mercaptobenzoxazole

2-Amino-4-chlorophenol (5.0 g, 35 mmol) and potassium hydroxide (2.34 g, 41.8 mmol) were dissolved in carbon disulfide (50 mL) and EtOH (75 mL), and the reaction mixture was heated to reflux. After 7 h, the reaction mixture was concentrated under reduced pressure. The material was taken up in EtOAc (100 mL) and 1M HCl (50 mL). The aqueous layer was separated, and the organic layer was washed with water (50 mL) and brine (50 mL). The organics were dried over Na2SO4, filtered, and concentrated under reduced pressure, yielding 5.71 g (89%) of the desired product as a brown solid. LC-MS: RT=7.60 min., [M+H]+=186.1.