4-Methylmorpholine → (S)-1-[4-(3-fluoro-benzyloxy)-phenyl]-5-oxo-pyrrolidine-3-carboxylic acid amide

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Reaction Steps

To (S)-1-[4-(3-fluoro-benzyloxy)-phenyl]-5-oxo-pyrrolidine-3-carboxylic acid (2.0 g, 6.07 mmol; enantiomeric purity (S):(R)>99.9:0.1) in tetrahydrofuran (40 mL), N-methylmorpholine (676 mg, 6.68 mmol) was added at 0° C. After stirring for 20 min, a solution of ethyl chloroformate (725 mg, 6.68 mmol) was added dropwise over 10 min, and stirring at 0° C. was continued for another 20 min. Ammonia (excess) was then bubbled for 15 min through the resulting suspension. The reaction mixture was warmed up to room temperature and stirred for 15 min. Water (50 mL) was added, and the tetrahydrofuran was evaporated in vacuo. The product, which precipitated, was collected by filtration, washed with water and tert-butyl methyl ether and dried at 45° C. in vacuo to afford (S)-1-[4-(3-fluoro-benzyloxy)-phenyl]-5-oxo-pyrrolidine-3-carboxylic acid amide (1.75 g, 88%). The purity of the product by HPLC was 98.9% (area) and the enantiomeric ratio (S):(R) was determined as 99.8:0.2.

Provenance & Evidence