Methyl iodide → 1-(2,6-Dimethylphenyl)-3-ethyl-4-methoxy-5-oxo-pyrrolidine-3-carboxylic acid methyl ester

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Reaction Steps

NaH (60% dispersed in mineral oil, 50 mg, ˜2.0 mmol) was added slowly to a cooled (0° C.) solution of 1-(2,6-dimethylphenyl)-3-ethyl-4-hydroxy-5-oxo-pyrrolidine-3-carboxylic acid methyl ester (prepared from step b, 146 mg, 0.5 mmol) in THF (5 mL). After stirring for 5 min, MeI (62.5 μL, 1 mmol) was added and the resulting reaction mixture was slowly warmed to room temperature and stirred further for 12 h. Saturated aqueous NH4Cl solution (10 mL) was added, and the solution was extracted with EtOAc (3×25 mL). The combined organic layer were washed with water (50 mL), brine (50 mL), dried (Na2SO4) and evaporated. The residue was purified by flash chromatography (SiO2, 10→50% EtOAc/hexanes) to give 1-(2,6-dimethylphenyl)-3-ethyl-4-methoxy-5-oxo-pyrrolidine-3-carboxylic acid methyl ester (70 mg, 46% yield). LC-MS: Rt (retention time): 2.31, 2.44 min (two diastereomers), MS: (ES) m/z 306.2 (M+H+).

Provenance & Evidence