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

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Reaction Conditions

Reaction Steps

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].

Provenance & Evidence