Uses
6-(morpholino-4-yl)pyridine-3-boronic acid pinacol ester, also known as 6-(4-morpholino)pyridine-3-boronic acid pinacol ester, is an important pharmaceutical and chemical intermediate.
Synthesis
Pinacol ester of bisboronic acid (1.25 g, 4.92 mmol) was dissolved in DMF (10 mL) under nitrogen protection and cooled to 0 °C. KOAc (1.21 g, 12.3 mmol) and Pd(dppf)Cl2-CH2Cl2 (0.1 g, 0.123 mmol) were added sequentially. The reaction mixture was heated to 80 °C and a solution of 5-bromo-2-morpholine pyridine (1.0 g, 4.1 mmol) in DMF (10 mL) was added dropwise. After the dropwise addition, the reaction was continued to be stirred at 80 °C for 10 hours. After completion of the reaction, the solvent was removed by evaporation. The residue was dissolved in ethyl acetate and the insoluble material was removed by filtration. The filtrate was evaporated and purified by column chromatography (eluent ratio: ethyl acetate:petroleum ether = 1:4) to afford 6-(morpholin-4-yl)pyridine-3-boronic acid pinacol ester (940 mg, 79% yield).
References
[1] Patent: WO2008/88881, 2008, A1. Location in patent: Page/Page column 41-42
[2] Patent: WO2009/155527, 2009, A2. Location in patent: Page/Page column 136