Synthesis
Tricyclohexylphosphine (2.85 g, 0.010 mol), tris(dibenzylideneacetone)dipalladium (4.65 g, 0.005 mol), and 25.0% of the total amount of the reaction flask were added to the reaction flask under argon protection using 6-bromoimidazo[1,2-a]pyridine (20.0 g, 0.102 mol) and pinacol bis(dibenzylideneacetone) (38.7 g, 0.152 mol) as the starting material. sodium acetate. Subsequently, 1,4-dioxane (200 mL) was added as a solvent and the reaction mixture was heated to 115-120°C and stirred for 24 hours. After the reaction was completed, it was cooled to room temperature and diluted with purified water (200 mL). The reaction mixture was extracted with ethyl acetate (200 mL x 2), the organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure to give a reddish brown solid. The solid was dissolved in tert-butyl methyl ether (30 mL) and stirred at room temperature for 2 hours. The light yellow solid was collected by filtration to give imidazo[1,2-a]pyridine-6-boronic acid (11.8 g, 72.0% yield).