1220696-34-3

73183-34-3

183208-22-2

1220696-34-3

Step 2: Synthesis of 1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrrolo[2,3-b]pyridine (Compounds 1-3) Under nitrogen protection, pinacol ester of bis(boronic acid) (11.26 g, 43.6 mmol), PdCl2(dppf) (814 mg, 1.11 mmol) and potassium acetate (6.53 g, 32.7 mmol) were sequentially added to a 50-bromo-1-methyl-1H-pyrrolo[2,3-b]pyridine (4.6 g, 21.8 mmol) containing 5-bromo-1-methyl-1H-pyrrolo[2,3-b]pyridine (4.6 g, 21.8 mmol). mL of 1,4-dioxane solution. The reaction mixture was stirred vigorously at 90°C for 8 hours. Upon completion of the reaction, the mixture was filtered and the filtrate was concentrated under reduced pressure to give the crude product compounds 1-3 (13.9 g), which could be used in the next step of the reaction without further purification. Mass spectrum (ESI) m/z: 259.1 [M + H]+.