a) 7-azaindole (100 g, 0.846 mol), Ni/AlO catalyst (12 g, 10 wt%), and toluene (200 g) were added to the autoclave and stirred and mixed homogeneously to obtain the reaction solution A; b) the autoclave was replaced with nitrogen for 8 times, followed by hydrogen for 4 times to ensure that the reaction system was oxygen-free; c) the reaction solution A was subjected to hydrogenation reaction at a pressure of 2 MPa hydrogen and 130 °C; d) after the completion of the reaction, the hydrogenation mixture was filtered to remove the catalyst to obtain the filtrate B; e) after distillation and recovery of the organic solvent from the filtrate B, 2,3-dihydro-1H-pyrrolo[2,3-b]pyridine (94.59 g, 93.4% yield) was obtained, and the purity of the product was analyzed by gas chromatography, which was ≥98%.