Diisopropylethylamine → (R)-2-(2-ethoxy-5-oxo-tetrahydrofuran-3-ylcarbamoyl)-pyrrolidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

A solution of (S)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (0.11 g, 0.5 mmol), di-isopropylethylamine (0.18 mL, 1.0 mmol), and tetramethylfluoroformamidinium hexafluorophosphate (TFFH) (0.13 g, 0.5 mmol) in dichloromethane (3 mL) was stirred at room temperature under nitrogen for 3 h. A solution of 4-[(triphenylphosphoranylidene)amino]-5-ethoxy-dihydrofuran -2-one (0.20 g, 0.5 mmol) in dichloromethane (3 mL) was added and the mixture was stirred for 24 h. The reaction was diluted with ethyl acetate, was washed with 10% sodium bisulfate, saturated sodium bicarbonate, and brine, was dried over sodium sulfate, and was evaporated. Purification by flash chromatography (SiO2) eluted with 1:1 ethyl acetate:hexanes provided (R)-2-(2-ethoxy-5-oxo-tetrahydrofuran -3-ylcarbamoyl)-pyrrolidine-1-carboxylic acid tert-butyl ester (0.11 g, 65% yield) as a very viscous, pale yellow oil.

Provenance & Evidence