[Synthesis]
Diethyl azodicarboxylate (DEAD) (520 μL, 3.3 mmol) was slowly added dropwise to an anhydrous tetrahydrofuran (THF) (13 mL) solution of triphenylphosphine (PPh3) (1.04 g, 3.96 mmol) at ambient temperature and under an inert atmosphere. Subsequently, the mixed solution was transferred to a round-bottomed flask containing a solution of anhydrous THF (41 mL) with 4-hydroxy-7-azaindole (222 mg, 1.65 mmol) and ethanol (115 μL, 1.98 mmol) under an inert atmosphere. The reaction mixture was stirred for 2 h at ambient temperature. After completion of the reaction, the solvent was removed by rotary evaporator. The resulting crude product was purified by column chromatography (eluent: dichloromethane/methanol, 98:2) to afford the target compound 4-ethoxy-1H-pyrrolo[2,3-b]pyridine (214 mg, 80% yield). The product was a solid with a melting point of 176-178 °C (ether); 1H NMR (300 MHz, CDCl3) δ 1.52 (t, 3H, J = 7.1 Hz, CH3), 4.26 (q, 2H, J = 7.1 Hz, CH2), 6.53 (d, 1H, J = 5.6 Hz, Harom), 6.59 (wide s, 1H, Harom) , 7.18 (broad s, 1H, Harom), 8.18 (d, 1H, J = 5.6 Hz, Harom), 9.64 (broad s, 1H, NH); mass spectrum (SI) m/z 163 (M + H+). |