反应详情

In an inert atmosphere and under exclusion of moisture, at 0° C. a solution of 6.9 g (102 mmol) of imidazol in 80 ml of dichloromethane was treated dropwise within 15 minutes with a solution of 2.2 ml (30 mmol) of thionylchloride in 30 ml of dichloromethane. After complete addition, the reaction mixture was left to warm to room temperature and stirring was continued for 30 minutes. Thereafter, a solution of 5.0 g (17 mmol) of (S)-2-tert-butoxycarbonylamino-3-hydroxy-propionic acid benzyl ester in 20 ml of dichloromethane was added dropwise at −78° C. After 1 hour at −78° C., the reaction mixture was left to warm to room temperature and stirring was continued overnight. For the working-up, the reaction mixture was quenched with 150 ml of a solution (10%) of citric acid. The organic layer was separated, washed with water, dried over sodium sulfate, and evaporated. The crude product (5.5 g of a colourless oil) was dissolved in 50 ml of ethyl acetate and cooled to 0° C. Thereafter, an aqueous solution (10%) of 9.0 g (29 mmol) of sodium metaperiodate, cooled to 0° C., and 0.36 g (2 mmol) of ruthenium(IV)oxide hydrate were added. After stirring at 0° C. for 30 minutes, the organic layer was separated, filtered over Dicalit and silica gel, and, finally, evaporated under reduced pressure. There were obtained 4.0 g (66%) of the (S)-2,2-dioxo-2λ6-[1,2,3]oxathiazolidine-3,4-dicarboxylic acid 4-benzyl ester 3-tert-butyl ester as a grey solid, [α]589=−21.51° (c=1.0% in MeOH), MS m/e (%): 356.0 (M−H+, 100).

1. additionAfter complete addition
2. waitthe reaction mixture was left
3. waitAfter 1 hour at −78° C.
4. waitthe reaction mixture was left
5. temperatureto warm to room temperature
6. stirringstirring
7. waitwas continued overnight
8. customthe reaction mixture was quenched with 150 ml of a solution (10%) of citric acid
9. customThe organic layer was separated
10. washwashed with water
11. dry with materialdried over sodium sulfate
12. customevaporated
13. dissolutionThe crude product (5.5 g of a colourless oil) was dissolved in 50 ml of ethyl acetate
14. temperaturecooled to 0° C
15. stirringAfter stirring at 0° C. for 30 minutes
16. customthe organic layer was separated
17. filtrationfiltered over Dicalit and silica gel
18. customfinally, evaporated under reduced pressure