91524-96-8

39856-58-1

140-89-6

91524-96-8

2-Bromo-3-aminopyridine (1.14 g, 6.59 mmol) and potassium ethylxanthate (2.324 g, 14.50 mmol) were used as starting materials, which were dissolved in anhydrous dimethylformamide (4 mL) and heated to react for 15 hours at 130 °C. After the reaction was completed, it was cooled to room temperature and the reaction mixture was diluted with water (150 mL). 5N hydrochloric acid (4 mL) was added and after stirring, the intermediate precipitated as a pale yellow solid, which was collected by filtration. The resulting solid was suspended in preheated ethyl acetate (200 mL) and dried by adding magnesium sulfate. After filtration, the filter cake was washed with preheated ethyl acetate (200 mL). The organic phases were combined and concentrated to dryness under reduced pressure. The residue was suspended in dichloromethane (50 mL), sulfuryl chloride (20 mL, 247 mmol) was added and the reaction was stirred for 1 hour at room temperature. Upon completion of the reaction, the solvent was evaporated under reduced pressure and the residue was partitioned between ethyl acetate (200 mL), ice (50 mL), water (100 mL) and saturated sodium bicarbonate solution (60 mL). The organic phase was separated, dried over magnesium sulfate and concentrated to dryness under reduced pressure. Finally, purification by silica gel column chromatography (dichloromethane to ethyl acetate gradient elution) afforded the target product 2-chlorothiazolo[5,4-b]pyridine (0.120 g, 0.703 mmol, 10.7% yield).