Hydrogen Bromide → Ethyl 2-bromo-2-cyclopropylacetate

To a solution of 2-cyclopropylacetic acid (24.7 g, 247 mmol) in anhydrous DCE (250 mL) was added thionyl chloride (22 mL, 302 mmol) dropwise for 5 minutes at 25° C. After being refluxed for 2 h, the reaction was cooled to room temperature, N-bromosuccinimde (53.6 g, 301 mmol) and hydrogen bromide (48% aqueous solution) (0.195 mL, 1.727 mmol) were added successively at 25° C. The resulted mixture was heated to refux for 96 h. After the reaction mixture was cooled to room temperature, absolute EtOH (200 mL) was added and the resulting dark brown solution was stirred at room temperature for an hour. The reaction mixture was concentrated under reduced pressure (35° C., 4.0 kilopascal) and the residue was suspended in carbon tetrachloride (300 mL) and passed through a glass filter. The filtrate was concentrated under reduced pressure (35° C., 4.0 kilopascal). Purification of the crude product by chromatography (silica gel, 330 g×2, 5% ethyl acetate/hexane) and concentration of the desired combined fractions under reduced pressure (35° C., 4.0 kilopascal) provided the title compound as a pale yellow liquid.

1. temperatureAfter being refluxed for 2 h
2. temperatureThe resulted mixture was heated
3. temperatureAfter the reaction mixture was cooled to room temperature
4. concentrationThe reaction mixture was concentrated under reduced pressure (35° C., 4.0 kilopascal)
5. filtrationfilter
6. concentrationThe filtrate was concentrated under reduced pressure (35° C., 4.0 kilopascal)
7. customPurification of the crude product by chromatography (silica gel, 330 g×2, 5% ethyl acetate/hexane) and concentration of the
8. customunder reduced pressure (35° C., 4.0 kilopascal)

ORD-Eintrag

ord-353b2a75df4e4a7da41d9bb84ac0aa03

Quelldatensatz

uspto-grants-2013_10

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08569341B2