Hydrochloric Acid → ethyl (4R)-2-oxo-1,3-thiazolidine-4-carboxylate

To the solution comprising 2 liters of water containing 180 g of sodium hydroxide was dissolved 175.6 g of L-cysteine monohydrochloride monohydrate under ice-cooling and under nitrogen atmosphere. To the solution was added dropwise 700 ml of a 1,4-dioxane solution containing 118.7 g of triphosgene at 25° C. to 29° C. over 1 hour and 30 minutes, and further stirred at the same temperature for 3 hours. To the reaction mixture was added conc. hydrochloric acid to adjust the mixture to weak acidic solution, and then, the solvent was removed under reduced pressure. To the concentrated residue was added 200 ml of toluene, and the solvent was removed again under reduced pressure. To the concentrated residue was added 700 ml of ethanol, 131 g of thionyl chloride was added to the mixture under ice-cooling over 40 minutes, and the resulting mixture was stirred for 19 hours while raising the temperature to room temperature. The solvent was removed under reduced pressure, and then, the concentrated residue was dissolved in 1 liter of ethyl acetate, and the mixture was successively washed with 700 ml of water, 300 ml of an aqueous saturated sodium bicarbonate solution and 500 ml of saturated brine. After the mixture was dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to give 162 g of ethyl (4R)-2-oxothiazolidin-4-carboxylate as oily product.

1. temperaturecooling and under nitrogen atmosphere
2. customthe solvent was removed under reduced pressure
3. additionTo the concentrated residue was added 200 ml of toluene
4. customthe solvent was removed again under reduced pressure
5. additionTo the concentrated residue was added 700 ml of ethanol, 131 g of thionyl chloride
6. additionwas added to the mixture under ice-
7. temperaturecooling over 40 minutes
8. stirringthe resulting mixture was stirred for 19 hours
9. customThe solvent was removed under reduced pressure
10. dissolutionthe concentrated residue was dissolved in 1 liter of ethyl acetate
11. washthe mixture was successively washed with 700 ml of water, 300 ml of an aqueous saturated sodium bicarbonate solution and 500 ml of saturated brine
12. dry with materialAfter the mixture was dried over anhydrous magnesium sulfate
13. customthe solvent was removed under reduced pressure

ORD record

ord-73392b68ef69459d902c9326eb628fe4

Source dataset

uspto-grants-2008_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07335778B2