Methanol → 1-Butyl-3-methoxypyridine-2-thione

To a solution of 1-butyl-3-methoxy-2-pyridone (2-034-02) (6.4 g) in toluene (150 mL) was added Lawesson's reagent (16.8 g), and the reaction mixture was heated under reflux. After the reaction mixture was stirred for 3 h, to the reaction mixture was added methanol (100 mL), and the reaction mixture was stirred for 30 min. After the solvent was evaporated under reduced pressure, to the reaction mixture were added water and ethyl acetate, and the organic layer was separated. The aqueous layer was extracted three times with ethyl acetate, and the combined organic layers were washed with water and brine, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure. The crude product was purified by silica gel column chromatography to give 1-butyl-3-methoxypyridine-2-thione (2-034-03) (5.6 g, 80%) as an oil.