Hydrochloric Acid → 5-Bromo-3-chlorothiophene-2-carboxylic acid

A solution of diisopropylamine (6.8 ml) in tetrahydrofuran (75 ml) was cooled to −78° C. under argon atmosphere, and thereto was added dropwise n-butyl lithium (1.59 M hexane solution, 30.5 ml). The reaction mixture was stirred at the same temperature for 30 minutes, and thereto was added dropwise a solution of 3-chloro-2-thiophenecarboxylic acid (3.92 g) in tetrahydrofuran (40 ml). The mixture was stirred at the same temperature for 30 minutes, and thereto was added dropwise 1,2-dibromo-1,1,2,2-tetrafluoroethane (6.0 ml). The mixture was stirred at the same temperature for one hour, and then, warmed to room temperature. The mixture was poured into a diluted aqueous hydrochloric acid solution, and the solution was extracted with ethyl acetate. The extract was washed with brine, and dried over sodium sulfate. The solvent was evaporated under reduced pressure and the residue was crystallized from a mixed solvent of diisopropyl ether and hexane to give 5-bromo-3-chloro-2-thiophenecarboxylic acid (3.79 g) as a yellow solid. ESI-Mass m/Z 239/241 (M−H). (2) The above 5-bromo-3-chloro-2-thiophenecarboxylic acid was treated in a manner similar to Reference Example 94 to give 5-bromo-3-chloro-2-(4-ethylphenylmethyl)thiophene as colorless oil.

1. stirringThe mixture was stirred at the same temperature for 30 minutes
2. stirringThe mixture was stirred at the same temperature for one hour
3. extractionthe solution was extracted with ethyl acetate
4. washThe extract was washed with brine
5. dry with materialdried over sodium sulfate
6. customThe solvent was evaporated under reduced pressure
7. customthe residue was crystallized from a mixed solvent of diisopropyl ether and hexane

ORD record

ord-d7abe2a095d44fc4a34c62f97cd1f6df

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08222219B2