General procedure for the synthesis of ethyl 1H-pyrrolo[2,3-B]pyridine-2-carboxylate from compound (CAS: 287384-79-6): compound 29 (9.7 g, 31.4 mmol, 1 equiv.) was dissolved in 6 N hydrochloric acid solution (50 mL) and stirred for 2 hr at 50 °C, followed by continued stirring at room temperature overnight. Upon completion of the reaction, the pH of the reaction mixture was adjusted to 13 with solid potassium carbonate (K2CO3), followed by extraction with ethyl acetate (EtOAc). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford the target product 30 (6.0 g, 100% yield). The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ 11.12 (br s, 1H), 8.59 (d, J = 4.8 Hz, 1H), 8.05 (dd, J = 8.0, 1.6 Hz, 1H), 7.19 (s, 1H), 7.18-7.15 (m, 1H), 4.46 (q, J = 6.8 Hz. 2H), 1.44 (t, J = 6.8 Hz, 3H).
![1H-Pyrrolo[2,3-b]pyridine-1,2-dicarboxylic acid, 2,3-dihydro-2-hydroxy-, 1-(1,1-dimethylethyl) 2-ethyl ester](/CAS/20210305/GIF/287384-79-6.gif)
![1H-Pyrrolo[2,3-b]pyridine-2-carboxylic acid, ethyl ester](/CAS/GIF/221675-35-0.gif)