800401-67-6

800401-66-5

800401-67-6

Step 2: Synthesis of ethyl 5-chloro-1H-pyrrolo[2,3-c]pyridine-2-carboxylate 10-b To a solution of 3-(2-chloro-5-nitropyridin-4-yl)-2-oxopropanoic acid ethyl ester 10-a (2.726 g, 10 mmol) in THF (80 mL) and EtOH (30 mL) was added a saturated ammonium chloride solution (50 mL). Subsequently, iron powder (2.747 g, 4.9 eq.) was added in batches at room temperature under vigorous stirring, and then the mixture was heated to reflux for 2 hours. Upon completion of the reaction, the mixture was cooled to room temperature, filtered through diatomaceous earth and washed with warm THF/ethanol (1:1, v/v). The filtrate was evaporated and the residue was dissolved in 100 mL of water with stirring and refluxing. The resulting precipitate was thermally filtered, washed twice with warm water and then dried under vacuum to give ethyl 5-chloro-1H-pyrrolo[2,3-c]pyridine-2-carboxylate 10-b (1.9 g, 84% yield). m/z = 225 (M + H)+; 1H NMR (400 MHz, DMSO-d6) δ ppm: 1.36 (t, J = 6.8 Hz, 3H), 4.39 (q, J = 6.7 Hz, 2H), 7.15 (s, 1H), 7.76 (s, 1H), 8.64 (s, 1H), 12.59 (br s, 1H).