Lithium Hydroxide → 4-Bromo-5-methyl-1H-pyrrole-2-carboxylic acid

Temperature

70 °C

Ethyl 4-bromo-5-methyl-1H-pyrrole-2-carboxylate (Intermediate 19, 16.5 g, 71.09 mmol) was dissolved anhydrous THF (100 ml) and was added to a preheated solution of 2 N lithium hydroxide (500 ml) at 70° C. The mixture was heated at 70° C. for 4 h and the solvent was removed in vacuo and the crude aqueous solution was cooled in an ice-bath and slowly acidified with 3 N HCl. The precipitate was extracted with EtOAc (3×100 ml), the organic extracts were washed with water, brine and dried with Na2SO4, treated with decolorizing charcoal for 1 h, filtered over celite and concentrated in vacuo. The brown solid was filtered and washed well with n-hexanes and dried in vacuo. (13 g).

1. customthe solvent was removed in vacuo
2. temperaturethe crude aqueous solution was cooled in an ice-bath
3. extractionThe precipitate was extracted with EtOAc (3×100 ml)
4. washthe organic extracts were washed with water, brine
5. dry with materialdried with Na2SO4
6. additiontreated with decolorizing charcoal for 1 h
7. filtrationfiltered over celite and
8. concentrationconcentrated in vacuo
9. filtrationThe brown solid was filtered
10. washwashed well with n-hexanes
11. customdried in vacuo

ORD record

ord-a9fe39d75e1b4759a7e9121ccbd6e006

Source dataset

uspto-grants-2010_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07709503B2