Ethanol → Ethyl 2,5-dibromothiophene-3-carboxylate

To a solution of 2,5-dibromothiophene-3-carboxylic acid (33.5 g) synthesized above in ethanol (300 mL) was added dropwise thionyl chloride (4.23 mL), and the mixture was stirred at room temperature overnight and then stirred with heating under reflux for 3 hr. The reaction mixture was concentrated under reduced pressure, saturated aqueous sodium hydrogen carbonate solution was added to the residue, and the mixture was extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=4:1, volume ratio) to give the title compound (33.4 g, 92%) as a white solid.

1. stirringstirred
2. temperaturewith heating
3. temperatureunder reflux for 3 hr
4. concentrationThe reaction mixture was concentrated under reduced pressure, saturated aqueous sodium hydrogen carbonate solution
5. additionwas added to the residue
6. extractionthe mixture was extracted with ethyl acetate
7. washThe extract was washed with brine
8. dry with materialdried over magnesium sulfate
9. concentrationconcentrated under reduced pressure
10. customThe residue was purified by silica gel column chromatography (ethyl acetate:hexane=4:1, volume ratio)

ORD record

ord-386319bb9a9c4362a22920536585471c

Source dataset

uspto-grants-2012_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08309580B2