Sodium Chloride → trans-5-Acetoxy-1,3-oxathiolane-2-carboxylic acid

Trans-5-hydroxy-1,3-oxathiolane-2-carboxylic acid (250 g, 1.67 mol) was added, in portions, to a stirred solution of acetic anhydride (0.625 L, 6.62 mol) and methanesulphonic acid (5 mL, 77 mmol) at room temperature. The resultant clear solution was stirred at room temperature for 60 minutes, slowly added to stirred aqueous 0.03M sodium bicarbonate solution (2.5 L) and then the mixture was stirred for a further 60 minutes. Sodium chloride (750 g, 12.83 mol) was added and the mixture was stirred for a further 30 minutes, clarified, and then extracted with isopropyl acetate (1×1.25 L, 3×0.625 L). The combined extracts were concentrated to 1.25 L under reduced pressure. Xylene (2.5 L) was added and the mixture reconcentrated to 1.25 L under reduced pressure. The xylene addition/reconcentration procedure was repeated and the resultant suspension was cooled to room temperature and stirred for 18 hours. The solid was collected by vacuum filtration, washed with xylene (2×0.25 L) and dried, in vacuo, at 40°-45° to give the title compound (265 g, 83%) which was shown, by comparison of 1H NMR spectra, to be a 65:35 mixture of the compounds of Examples 3 and 4.

1. additionslowly added
2. stirringthe mixture was stirred for a further 60 minutes
3. stirringthe mixture was stirred for a further 30 minutes
4. extractionextracted with isopropyl acetate (1×1.25 L, 3×0.625 L)
5. concentrationThe combined extracts were concentrated to 1.25 L under reduced pressure
6. additionXylene (2.5 L) was added
7. additionThe xylene addition/reconcentration procedure
8. temperaturethe resultant suspension was cooled to room temperature
9. stirringstirred for 18 hours
10. filtrationThe solid was collected by vacuum filtration
11. washwashed with xylene (2×0.25 L)
12. customdried, in vacuo, at 40°-45°

ORD record

ord-d1b23f64c5384aacbb06900702550235

Source dataset

uspto-grants-1997_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05693787