Potassium tert-butoxide → 7-Hydroxy-2-(4-trifluoromethyl-phenyl)-thiazolo[4,5-c]pyridine-6-carboxylic acid ethyl ester

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A mixture of 4-[(tert-butoxycarbonyl-ethoxycarbonylmethyl-amino)-methyl]-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic acid ethyl ester (302 mg, 0.58 mol) in THF (5 mL) was added drop wise a solution of 1 M KOtBu in THF (702 μL, 0.70 mmol) at −78° C. The mixture was stirred at −78° C. for 15 min, warmed to room temperature and stirred at that temperature for 1.5 h before it was quenched with brine, extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo to a yellow foam (469 mg). It was dissolved in dichloromethane (10 mL) and TFA (2.5 mL) was added. The mixture was stirred at room temperature for 1 h before it was concentrated in vacuo. It was redissolved in dichloromethane, triethylamine (923 μL) was added. The mixture was stirred under air overnight before it was partitioned between dichloromethane and water, the organic layer was washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel with a gradient of ethyl acetate and dichloromethane to give the title compound as a white solid (257 mg): MS: (+) m/z 330.0 (M+1).

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