Potassium Carbonate → 2-(7-Hydroxy-2-oxo-2H-chromen-3-yl)-4-methyl-thiazole-5-carboxylic acid ethyl ester

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Reaction Steps

To a solution of 7-hydroxy-2-oxo-2H-chromene-3-carbothioic acid amide (66 mg, 0.3 mmol) in anhydrous N,N-dimethylformamide (5 mL), freshly dried K2CO3 (263 mg, 1.9 mmol) was added followed by 2-chloro-3-oxo-butyric acid ethyl ester (79 μL, 94 mg, 0.54 mmol) and the mixture was stirred at room temperature for 19 h. The mixture was poured into water (25 mL) and extracted first with chloroform (3×10 mL) and, after saturation with NaCl, with tetrahydrofuran (3×10 mL). The combined organic extracts were dried over MgSO4 and concentrated. The residue was dissolved in chloroform (8 mL), pyridinium p-toluenesulfonate (7.5 mg, 0.03 mmol) was added and the mixture was stirred at 60° C. for 4.5 h. After cooling, the solution was washed with brine (3×5 mL), dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica, eluting with a 9:1:0.1 mixture of chloroform, methanol and cc. NH4OH. The title compound (14.5 mg, 0.044 mmol, 14.7%) was obtained as a yellow solid.

Provenance & Evidence