Ammonium Chloride → 1-(2,6-Dimethylphenyl)-3-(2-methylallyl)-5-oxo-pyrrolidine-3-carboxylic acid methyl ester

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Reaction Steps

LHMDS (1 M solution in THF, 83 mL, 83 mmol) was added slowly to a cooled (−50° C.) solution of 1-(2,6-dimethylphenyl)-5-oxo-pyrrolidine-3-carboxylic acid methyl ester (17 g, 68.83 mmol) in THF (170 mL). After 5 min, 3-bromo-2-methylpropene (13.8 mL, 136.8 mmol) was added slowly at −50° C. and the resulting reaction mixture was warmed to room temperature and stirred for 2 h. Saturated aqueous NH4Cl solution (50 mL) was added, and the aqueous was extracted with EtOAc (3×100 mL). The combined organic layers were washed with water (100 mL), brine (100 mL), dried (Na2SO4) and evaporated. The residue was purified by automated flash chromatography (SiO2, 20→60% MTBE/hexanes) to give 1-(2,6-dimethylphenyl)-3-(2-methylallyl)-5-oxo-pyrrolidine-3-carboxylic acid methyl ester (10.9 g, 53% yield). LC-MS: R, (retention time): 2.44 min, MS: (ES) m/z 302.1 (M+H+).

Provenance & Evidence