ethyl 5-hydroxymethyl-1,4-dimethyl-1H-pyrrole-2-carboxylate → 1,4,5-trimethyl-1H-pyrrole-2-carboxylic acid

A mixture of ethyl 5-hydroxymethyl-1,4-dimethyl-1H-pyrrole-2-carboxylate (2.2 g), ethanol (15 ml), and palladium-carbon (2.2 g) was stirred at room temperature for 2 hours under a hydrogen atmosphere of 3 atmospheres. The insolubles of the reaction mixture were separated by filtration through Celite and the filtrate was concentrated to about 10 ml under reduced pressure. THF (10 ml) was added to the residue, and a 1 M aqueous sodium hydroxide solution (20 ml) was further added at room temperature, followed by stirring at room temperature for 13 days. The reaction mixture was washed with diethyl ether, and 1 M hydrochloric acid (20 ml) was added to the aqueous layer under ice-cooling. The solid precipitated was collected by filtration and washed with water to obtain 1,4,5-trimethyl-1H-pyrrole-2-carboxylic acid (0.79 g).

1. customThe insolubles of the reaction mixture were separated by filtration through Celite
2. concentrationthe filtrate was concentrated to about 10 ml under reduced pressure
3. additionTHF (10 ml) was added to the residue
4. additiona 1 M aqueous sodium hydroxide solution (20 ml) was further added at room temperature
5. stirringby stirring at room temperature for 13 days
6. washThe reaction mixture was washed with diethyl ether, and 1 M hydrochloric acid (20 ml)
7. additionwas added to the aqueous layer under ice-
8. temperaturecooling
9. customThe solid precipitated
10. filtrationwas collected by filtration
11. washwashed with water

ORD record

ord-f0ddd5cf5ba747468d5da868cece4134

Source dataset

uspto-grants-2011_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08030489B2