Ethanol → 5-formyl-4-methyl-1H-pyrrole-2-carboxylic Acid

HRID 1372403Notes

Reaction equation

C([O:3][C:4]([C:6]1[NH:7][C:8]([CH:12]=[O:13])=[C:9]([CH3:11])[CH:10]=1)=[O:5])C.C(O)C.[OH-].[K+]>O>[CH:12]([C:8]1[NH:7][C:6]([C:4]([OH:5])=[O:3])=[CH:10][C:9]=1[CH3:11])=[O:13]

Participants

Conditions

Temperature: 100 °C

Procedure

5-Formyl-4-methyl-1H-pyrrole-2-carboxylic acid ethyl ester was dissolved in water (35 mL) and ethanol (15 mL) with stirring. Potassium hydroxide (2 equivalents, 0.5 g) was added and the mixture heated to 100° C. After 1 hour the mixture was cooled to room temperature and concentrated to about ⅔ volume. The water layer was acidified to pH 3 using 2 N hydrochloric acid. The white solid was collected by vacuum filtration and washed with water to afford 0.67 g (68% yield) of 5-formyl-4-methyl-1H-pyrrole-2-carboxylic acid as a tan solid. 1H-NMR (360 MHz, dimethylsulfoxide-d6) δ 12.92 (br s, 1H, COOH), 12.48 (br s, 1H, NH), 9.76 (s, 1H, CHO), 6.63 (s, 1H, pyrrole CH), 2.28 (s, 3H, CH3). MS m/z 152 [M+−1].

Workup

temperatureAfter 1 hour the mixture was cooled to room temperature
concentrationconcentrated to about ⅔ volume
filtrationThe white solid was collected by vacuum filtration
washwashed with water

Sources & evidence

ORD record: ord-5fdbdbb9f30245f8b5cbd5955ccf0ea3
Source dataset: uspto-grants-2007_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07157577B2

Reaction notes

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