Synthesis
General procedure for the synthesis of 5-bromo-2-mercaptobenzothiazole from 5-bromobenzothiazole: 5-bromobenzothiazole (214.08 mg, 1.0 mmol), 1,3-propanedithiol (325 μL, 3.0 mmol), potassium carbonate (552 mg, 4.0 mmol), and DMSO (2 mL) were added into a reaction tube equipped with a magnetic stirrer. The reaction system was displaced three times with nitrogen to remove air, followed by stirring the reaction for 12 h in an oil bath at 120 °C. Upon completion of the reaction, the reaction mixture was transferred to a dispensing funnel and washed with an appropriate amount of water. The pH of the aqueous phase was adjusted to 1-3 with dilute hydrochloric acid, followed by extraction of the organic phase with dichloromethane. The organic phases were combined and dried with anhydrous magnesium sulfate. After filtration, the organic phase was concentrated under reduced pressure and the resulting crude product was purified by column chromatography to give a pink solid product (112.4 mg, 45.7% yield).
