3.2.3. Synthesis of Ethyl, 1H-Indole-2-Carboxylate (5)

To a stirred solution of 1H-indole-2-carboxylic acid (4) (1.5 g, 9.31 mmol) in dry ethanol (25 mL), sulfuric acid (0.5 mL) was added as catalyst. The reaction mixture was refluxed for 1.5 h. After the reaction was complete, water (25 mL) was added, and the mixture was extracted with ethyl acetate (3 × 50 mL). The combined organic phases were washed with brine, water, and dried over anhydrous Na₂SO₄. The solvent was evaporated under vacuum to give ethyl-1H-indole-2-carboxylate (6) as a white powder [65]. M.p. 126–127 °C (Lit. M.p. 123–124 °C). ¹H NMR (CDCl₃) δ 1.43 (t, J = 7.4 Hz, 3H, CH₃), 4.51 (q, J = 7.2 Hz, 2H, CH₂), 6.96–6.99 (m, 1H, Ar), 7.12 (d, J = 7.0 Hz, 2H, Ar), 7.35 (d, J = 7.2 Hz, 2H, Ar), 9.31 (s, 1H, NH).