Trifluoroacetic acid → 2-{[4-(2-Hydroxyethyl)-1,3-thiazol-2-yl]thio}-2-methylpropionic acid ethyl ester

2-{[4-(2-Hydroxyethyl)-1,3-thiazol-2-yl]thio}-2-methylpropionic acid tert-butyl ester (8.4 g) obtained in Example 4 was dissolved in dichloromethane (50 mL), trifluoroacetic acid (50 mL) was added, and the mixture was stirred at room temperature for 12 hr. The reaction mixture was concentrated under reduced pressure, and the residue was dissolved in ethanol (100 mL). Thionyl chloride (8 mL) was added under ice-cooling, and the mixture was refluxed for 4 hr. Under ice-cooling, saturated aqueous sodium hydrogen carbonate solution was added to the reaction mixture, and the solvent was concentrated under reduced pressure. The mixture was extracted with ethyl acetate, and the organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel chromatography (elution solvent; hexane:ethyl acetate=1:1) to give the title compound (6.7 g) as a colorless oil.

1. concentrationThe reaction mixture was concentrated under reduced pressure
2. dissolutionthe residue was dissolved in ethanol (100 mL)
3. additionThionyl chloride (8 mL) was added under ice-
4. temperaturecooling
5. temperaturethe mixture was refluxed for 4 hr
6. temperatureUnder ice-cooling
7. additionsaturated aqueous sodium hydrogen carbonate solution was added to the reaction mixture
8. concentrationthe solvent was concentrated under reduced pressure
9. extractionThe mixture was extracted with ethyl acetate
10. washthe organic layer was washed with saturated brine
11. dry with materialdried over anhydrous sodium sulfate
12. customThe solvent was evaporated under reduced pressure
13. customthe residue was purified by silica gel chromatography (elution solvent; hexane:ethyl acetate=1:1)

ORD record

ord-b498a9767faf497c9014654768252974

Source dataset

uspto-grants-2011_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08026370B2