Triethylamine → 2-(2-Chloro-phenyl)-4-ethyl-oxazole-5-carboxylic acid 2,5-dioxo-pyrrolidin-1-yl ester

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Reaction Conditions

Reaction Steps

To a stirred slurry of 2-(2-chloro-benzoylamino)-butyric acid (2.84 g, 11.8 mmol) in 60 mL of anhydrous tetrahydro furan, was added oxalyl chloride (10.1 mL, 118 mmol). The mixture was stirred at 50° C. overnight and then the solvent was evaporated in vacuo. The oily residue was treated with toluene and evaporated to remove trace of oxalyl chloride. The residue was then cooled in an ice bath and triethylamine (3.4 mL, 23.6 mmol) was added followed by the addition of 1-hydroxy-pyrrolidine-2,5-dione. The reaction mixture was stirred at 50° C. overnight before the solvent was removed in vacuo. The residue was then purified by flash chromatography (Merck silica gel 60, 230-400 mesh, 5-60% ethyl acetate in hexane for 25 min) to give 2-(2-chloro-phenyl)-4-ethyl-oxazole-5-carboxylic acid 2,5-dioxo-pyrrolidin-1-yl ester (997 mg, 25% yield) as a light yellow solid. LCMS calcd for C16H13ClN2O5 (m/e) 348, obsd 349 (M+H).

Provenance & Evidence