Carbon Dioxide → 5-Bromo-3-methyl-1-benzothiophene-2-carboxylic acid

Temperature

-78 °C

A mixture of diisopropylamine (4.44 g.) and potassium t-butoxide (5.02 g.) in dry ether was cooled to -78° C. under an atmosphere of dry nitrogen and n-butyl lithium (28.4 ml. of 1.55 M solution in hexane) was added with stirring over 5 minutes. The mixture was stirred at -78° for 30 minutes and then a solution of 5-bromo-3-methylbenzo[b]thiophene (9.10 g.) in dry ether (25 ml.) was added over 5 minutes. The resulting mixture was stirred at -78° C. for 30 minutes and then poured onto a mixture of crushed solid carbon dioxide and ether. When all the carbon dioxide had evaporated the mixture was shaken with water and the ether layer was separated. The aqueous layer was acidified with acetic acid and the solid was filtered off, washed with water and crystallized from acetic acid to give 5-bromo-3-methylbenzo[b]thiophene-2-carboxylic acid (7.30 g.), m.p. >300°.

1. stirringThe mixture was stirred at -78° for 30 minutes
2. stirringThe resulting mixture was stirred at -78° C. for 30 minutes
3. customWhen all the carbon dioxide had evaporated the mixture
4. stirringwas shaken with water
5. customthe ether layer was separated
6. filtrationthe solid was filtered off
7. washwashed with water
8. customcrystallized from acetic acid

ORD record

ord-e94f117b14f54c279bcbdc5096a04db5

Source dataset

uspto-grants-1983_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04410539