To a solution of 4-[5-(6-hydroxymethyl-4-oxo-4H-pyran-3-yloxy)-pentyloxy]-7-trifluoromethyl-quinoline-3-carboxylic acid ethyl ester 13 (330 mg, 0.67 mmol) in CH2Cl2 (15 mL) was added at 0° C. triethylamine (37 μL, 0.26 mmol), methanesulfonyl chloride (62 μL, 0.80 mmol). The solution was stirred at RT for 1 h. Dichloromethane (50 mL) was added and the solution was washed with water (2×100 mL), dried over MgSO4, filtered and evaporated. The crude product was purified by column chromatography on silica using as eluent CH2Cl2:MeOH=95:15. (5-(5-(6-(Trifluoromethyl)quinolin-4-yloxy)pentyloxy)-4-oxo-4H-pyran-2-yl)methylmethanesulfonate 18 was obtained (246 mg, 65% yield) as a pale yellow oil.
