2-Amino-3-cyanopyridine-5-boronic Acid Pinacol Ester

Synthesis

2-amino-5-bromonicotinonitrile (50 g, 0.224 mol), bis (pinacolato) diboron (85.6 g, 0.337 mol), KOAc (44.1 g, 0.449 mol) and Pd (dppf) Cl2. CH2C12 (2.77 g, 3.4 mmol) was charged into a flask. Dioxane (400 mL) was added. The reaction mixture was stirred at 100 ℃ for 2 h under Ar. When LC-MS indicated that the reaction was completed, the mixture was cooled to room temperature. Subsequently, the mixture was filtered through diatomite, concentrated, diluted with a mixture of ethyl acetate and hexane (3:1, 1000 mL), filtered through silica gel (300-400 mesh), concentrated, crystallized and dried to give 2-Amino-3-cyanopyridine-5-boronic Acid Pinacol Ester (32 g, 66%) as a white solid.