A 50 mL round bottom flask is charged with 2-(4-(4-hydroxybutyl)phenyl methyl)thio 3-methyl chromen-4-one (6.0 g, 16.9 mmol) and pyridine (15 mL) is added to it. Toluenesulfonyl chloride (25.4 mmol) is then added in one lot and the mixture is stirred for 8 hours after which water and ethyl acetate are added to it. The contents are poured into a separatory funnel and the layers separated. The organic layer is washed with 5% CuSO4 (2×10 mL) and then with water and brine. It is then dried over magnesium sulfate, filtered, and concentrated in vacuo. The residue obtained is purified by silica gel flash chromatography (ethyl acetate:hexanes) to afford the product.
