Methanol → 5-Formyl-2-methyl-4-phenyl-1H-pyrrole-3-carboxylic Acid

Participants

Reaction Steps

5-Formyl-2-methyl-4-phenyl-1H-pyrrole-3-carboxylic acid ethyl ester was dissolved in water (100 mL) and methanol (45 mL) with stirring. Added KOH (2 eq. 1.9 g) and heated in 100° C. After 2.5 h, cooled to room temperature and the remaining ester was removed by extracting into ethyl acetate (200 mL), dried and concentrated. The water layer was acidified to pH=3 using 2N HCl. The white solid was removed by filtration, rinsing with water. The solid was re-concentrated from toluene, triturated with hexanes and dried to afford 2 g (52%) of an off-white solid. 1H NMR (360 MHz, DMSO-d6) δ 12.46 (br s, 1H, CO2H), 11.95 (s, 1H, NH), 9.08 (s, 1H, CHO), 7.36 (s, 5H, ArH), 2.49 (s, 3H, CH3). MS m/z (relative intensity %, ion) found 229 (100, M+); calc. 229.2.

Provenance & Evidence