[CH3:1][O:2][C:3]([C:5]1[CH:10]=[CH:9][C:8]([OH:11])=[CH:7][N:6]=1)=[O:4].[F:12][C:13]([F:21])([F:20])[CH2:14]OS(C)(=O)=O.C([O-])([O-])=O.[K+].[K+]>C(#N)C>[CH3:1][O:2][C:3]([C:5]1[CH:10]=[CH:9][C:8]([O:11][CH2:14][C:13]([F:21])([F:20])[F:12])=[CH:7][N:6]=1)=[O:4]A mixture of 5-Hydroxy-pyridine-2-carboxylic acid methyl ester 2 (0.5 g, 3.26 mmol), methanesulfonic acid 2,2,2-trifluoro-ethyl ester (1.0 g, 5.34 mmol) and K2CO3 (1.4 g, 9.8 mmol) in acetonitrile (50 mL) was stirred overnight. The solid was filtered off and the filtrate was concentrated. The residue was purified by column chromatography (eluting with hexane and ethyl acetate 1:1) to afford 5-(2,2,2-Trifluoro-ethoxy)-pyridine-2-carboxylic acid methyl ester 3 as a white solid. Yield: 0.437 g, 57.1%.
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