Reaktion #69540

Reaktionsgleichung

1,2-dibromotetrafluoroethane

ammonium chloride

n-butyllithium

tert-butyl(6-methoxypyrazolo[5,1-b][1,3]thiazol-7-yl)carbamate

→

title compound

Ausbeute 66.9%

tert-Butyl(3-bromo-6-methoxypyrazolo[5,1-b][1,3]thiazol-7-yl)carbamate

Ausbeute 66.9%

Lösungsmittel

acetic acid

n-heptane ethyl acetate

ethyl acetate

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGAfter stirring the mixture at −78° C. for 40 minutes
2. 2
   workup.STIRRINGthe mixture was stirred for two hours
3. 3
   Temperaturwhile warming to mom temperature
4. 4
   workup.STIRRINGAfter thoroughly shaking the mixture
5. 5
   Sonstigethe organic layer was separated
6. 6
   Waschenthe organic layer was washed with brine
7. 7
   Trocknendried over anhydrous magnesium sulfate
8. 8
   FiltrationThe mixture was filtered
9. 9
   workup.DISTILLATIONthe solvent in the filtrate was distilled off under reduced pressure
10. 10
    SonstigeThe residue was purified by silica gel column chromatography (a mixed solvent of n-heptane and ethyl acetate

Vorschrift

To a mixture of tert-butyl(6-methoxypyrazolo[5,1-b][1,3]thiazol-7-yl)carbamate (16.5 g, 61.4 mmol) and THF (410 mL) was added n-butyllithium (2.77 M n-hexane solution: 62.1 mL, 172 mmol) while stirring at −78° C. After stirring the mixture at −78° C. for 40 minutes, 1,2-dibromotetrafluoroethane (10.2 mL, 86 mmol) was added, and the mixture was stirred for two hours while warming to mom temperature. A saturated aqueous solution of ammonium chloride and ethyl acetate were added to the mixture, and then acetic acid was added so that the mixture became weakly acidic. After thoroughly shaking the mixture, the organic layer was separated and the organic layer was washed with brine and dried over anhydrous magnesium sulfate. The mixture was filtered, and then the solvent in the filtrate was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (a mixed solvent of n-heptane and ethyl acetate: n-heptane/ethyl acetate=1/0 then 4/1) to obtain the title compound (14.3 g, 41.1 mmol).

Quelle