Lithium Hydroxide → 5-Formyl-3-methyl-1H-pyrrole-2-carboxylic acid

Participants

Reaction Steps

Lithium hydroxide (8.73 g, 36.44 mmol) was added to the 5-formyl-3-methyl-1H-pyrrole-2-carboxylic acid ethyl ester (1.32 g, 7.27 mmol) in methanol (27 mL) and water (9 mL). The mixture was stirred at room temperature for over the weekend. The reaction was diluted with water (10 mL), evaporated most of the methanol and washed with ether. The aqueous layer was acidified with 1N HCl (37 mL) to pH=2, extracted with ethyl acetate. Washed with brine, dried and concentrated. The residue was washed with dichloromethane and filtered to give 0.98 g (88%) of 5-formyl-3-methyl-1H-pyrrole-2-carboxylic acid as a tan solid. 1H NMR (360 MHz, DMSO-d6) δ 12.87 (br s, 1H, COOH), 12.41 (br s, 1H, NH), 9.63 (s, 1H, CHO), 6.74 (s, 1H), 2.26 (s, 3H, CH3).

Provenance & Evidence