394223-03-1

221675-35-0

394223-03-1

Step c: Synthesis of 1H-pyrrolo[2,3-b]pyridine-2-carboxaldehyde [0452] A solution of ethyl 1H-pyrrolo[2,3-b]pyridine-2-carboxylate (190 mg, 1.0 mmol) in THF (5.0 mL) was slowly added dropwise at -20 °C to a suspension of LiAlH4 (42 mg, 1.1 mmol) in THF (10.0 mL) in a suspension of LiAlH4 (42 mg, 1.1 mmol). The reaction mixture was stirred continuously at -20 °C for 2 hours. Upon completion of the reaction, the reaction was quenched with saturated NH4Cl solution (10.0 mL). The reaction mixture was filtered and the filter cake was washed with ethyl acetate. The combined filtrates were sequentially washed with brine, dried over anhydrous Na2SO4 and then concentrated to afford 120 mg of 1H-pyrrolo[2,3-b]pyridine-2-carbaldehyde in 67% yield. The resulting product was used directly in the next reaction without further purification.