Step 1: To degassed N,N-dimethylacetamide (200 mL), 4-chloro-7-azaindole (30.0 g, 196.7 mmol), zinc cyanide (23.1 g, 196.7 mmol), zinc powder (1.28 g, 19.67 mmol), tris(dibenzylideneacetone)dipalladium (3.6 g, 3.93 mmol) and diphenylphosphino ferrocene (4.36 g, 7.86 mmol). The reaction mixture was heated at 120 °C for 18 hours. After completion of the reaction, it was cooled to room temperature and the mixture was poured into crushed ice (1.5 kg) and the solid product was collected by filtration. The solid product was washed with ethyl acetate (2 x 1500 mL) and filtered after stirring for 0.5 h at a time. The filtrates were combined, concentrated and crystallized from ethyl acetate to give 1H-pyrrolo[2,3-b]pyridine-4-carbonitrile (22.0 g, 78% yield).1H NMR (400 MHz, DMSO-d6): δ 12.20 (br s, 1H), 8.41 (d, J = 4.8 Hz, 1H), 7.84 (s, 1H), 7.56 (d, J = 4.8 Hz, 1H), 6.65 (d, J = 1.6 Hz, 1H).
