To a solution 2-[4-(4-hydroxy-butyl)-benzylsulfanyl]-3-methyl-chromen-4-one (300 mg, 0.85 mmol) dissolved in anhydrous dichloromethane (8.0 mL) was added TsCl (194 mg, 1.01 mmol), DMAP (124 mg, 1.01 mmol) and TEA (0.213 mL, 1.52 mmol). The reaction mixture continued stirring at room temperature. After 3 hours the reaction mixture was diluted with water. The aqueous layer was separated and extracted with ethyl acetate (3×). All combined organic layers were dried over Na2SO4, filtered, and concentrated to yield an oil. The crude material was purified using silica gel chromatography (1:1 pentane: ethyl acetate) to yield toluene-4-sulfonic acid 4-[4-(3-methyl-4-oxo-4H-chromen-2-ylsulfanylmethyl)-phenyl]-butyl ester (280 mg, 0.55 mmol) in moderate yield (65%).1H (CDCl3, 600 MHz): δ 8.18 (1H, dd, J=7.9, 1.3 Hz), 7.77 (2H, d, J=8.2 Hz). 7.62 (1H, m), 7.39 (2H, t, J=8.0 Hz), 7.33 (2H, d, J=8.0 Hz), 7.30 (2H, d, J=8.0 Hz), 7.07 (2H, d, J=8.0 Hz), 4.37 (2H, s), 4.02 (2H, t, J=5.8 Hz), 2.55 (2H, t, J=7.3 Hz), 2.05 (3H, s), 1.65 (4H, m); 13C (CDCl3, 150 MHz): δ 175.5, 162.2, 156.7, 144.9, 141.5, 134.1, 133.4, 133.0, 130.0, 129.1, 129.0, 128.1, 126.5 125.3, 122.9, 117.5, 117.0, 70.5, 35.3, 34.9, 28.6, 27.2, 21.8, 10.8.; HRMS calcd for C28H28O5S2 509.1450:, found 509.1441
