Potassium Hydroxide → 4-Methoxy-1H-indole-2-carboxylic acid

Participants

Reaction Steps

A mixture of 4-methoxy-1H-indole-2-carboxylic acid methyl ester (0.448 g, 2.18 mmol) in potassium hydroxide (0.612 g, 10.9 mmol) and EtOH (111 mL) was stirred at ambient temperature for about 16 h. The reaction mixture was concentrated in vacuo and the residue portioned between water (10 mL) and Et2O (10 mL). The aqueous portion was separated and acidified by the addition of 1N aqueous HCl, then extracted with Et2O (2×10 mL). The combined organic extracts were washed with brine (10 mL), dried over MgSO4, filtered, and concentrated in vacuo to give 4-methoxy-1H-indole-2-carboxylic acid (0.371 g, 89%) as a white solid which was used in subsequent reactions without further purification. 1H NMR (d6 DMSO, 400 MHz) 12.84 (1H, s), 11.74 (1H, s), 7.15 (1H, t), 7.00-7.03 (2H, m), 6.52 (1H, d), and 3.87 (3H, s).

Provenance & Evidence