Morpholine → (S)-4-((5-Oxo-2-pyrrolidinyl)carbonyl)morpholine

Participants

Reaction Steps

L-pyroglutamic acid methyl ester (23.91 g, 177 mmol), morpholine (21.8 g, 250 mmol) and 4-dimethylaminopyridine (0.2 g, 1.64 mmol) are heated under reflux in toluene (130 ml) for 12 hours. The product precipitates as an oil. The oil is separated from the toluene, diluted with dichloromethane (100 ml) and washed successively with 0.1 M HCl, 0.1 M NaOH and water (50 ml each). The dichloromethane phase is concentrated to obtain a suspension, which is filtered yielding the crude product. The crude product is dissolved in THF (200 ml) at 45° C. and, upon cooling in an ice bath, (S)-5-morpholine-4-carbonyl)pyrrolidin-2-one precipitates as white crystals. Enantiopurity (GC) 88.7% (S)-Enantiomer.

Provenance & Evidence