Methanol → Methyl 5-oxo-L-prolinate

A 500 g sample of L-pyroglutamic acid was added to 2.8 L of anhydrous methanol, 28 mL of H2SO4 was added, and the mixture was stirred for 4 hr at 60° C. The reaction mixture was cooled to room temperature, 262 g of NaHCO3 was added, and the mixture was stirred for an additional 16 hr. The mixture was dried by addition of 314 g of Na2SO4 with stirring for 1 hr, then the mixture was filtered and the solvent was evaporated under vacuum to yield a pale yellow oil. The oil was dissolved in THF, and a small amount of unreacted acid was filtered off. The THF was removed under vacuum, and the residual oil was dried by azeotropic distillation with toluene.

1. additionwas added
2. temperatureThe reaction mixture was cooled to room temperature
3. stirringthe mixture was stirred for an additional 16 hr
4. dry with materialThe mixture was dried by addition of 314 g of Na2SO4
5. stirringwith stirring for 1 hr
6. filtrationthe mixture was filtered
7. customthe solvent was evaporated under vacuum
8. customto yield a pale yellow oil
9. filtrationa small amount of unreacted acid was filtered off
10. customThe THF was removed under vacuum
11. dry with materialthe residual oil was dried by azeotropic distillation with toluene

ORD record

ord-0c770679fe32403da5c7fc2799431ed7

Source dataset

uspto-grants-1995_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05424444