Water → 6-Fluoro-3-methyl-4-trifluoromethane-sulfonyloxynaphthalene-2-carboxylic acid methyl ester

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Reaction Steps

Trifluoromethanesulfonic anhydride (3.52 mL, 20.8 mmol) was added drop-wise over a period of 30 minutes to a 0° C. solution of 6-fluoro-4-hydroxy-3-methyl-naphthalene-2-carboxylic acid methyl ester (3.75 g, 16.0 mmol) in dichloromethane (120 mL) and pyridine (1.95 mL, 24.2 mmol). The resulting mixture was allowed to warm slowly to room temperature with stirring, and the reaction mixture was stirred at room temperature for 3.5 hours. After this time, the reaction mixture was cooled to 0° C. Water (150 mL) was added, and the organic phase was separated. The organic phase was dried over Na2SO4, filtered, and concentrated to afford a brown solid. Flash chromatography (Aspire FlashReady™, 50 μm, 10%-18% ethyl acetate in hexane) gave 6-fluoro-3-methyl-4-trifluoromethane-sulfonyloxynaphthalene-2-carboxylic acid methyl ester as 4.52 g (77%) of a yellow, crystalline solid. HRMS (EI+) cald. for C14H10F4O5S [M+] 366.0185, obsd. 366.0186.

Provenance & Evidence