Synthesis
General procedure for the synthesis of 6-fluoro-2-pyridineboronic acid pinacol ester from 2-bromo-6-fluoropyridine and bis(pinacolato)diboron as raw materials: under nitrogen protection, Pd(dppf)2Cl2-CH2Cl2 (102 mg, 0.14 mmol) was added to a degassed 2-bromo-6-fluoropyridine (410 mg, 2.33 mmol), bis(pinacolato)diboron ( 828 mg, 3.26 mmol) and KOAc (685 mg, 6.99 mmol) in a solution of dioxane (6 mL). The reaction mixture was heated with stirring at 115 °C for 1 hour. After completion of the reaction, it was cooled to room temperature and the solvent was removed by distillation under reduced pressure. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol, 100:0 to 90:10), and the fraction containing the target product was collected and concentrated under reduced pressure to give pinacol ester of 6-fluoro-2-pyridineboronic acid (400 mg, 76% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 7.78 (td, J = 8.1, 7.2 Hz, 1H), 7.70 (ddd, J = 6.9, 2.8, 0.9 Hz, 1H), 6.98 (ddd, J = 8.1, 2.7, 0.9 Hz, 1H), 1.38 (s, 12H).
References
[1] Patent: US2014/275120, 2014, A1. Location in patent: Paragraph 0531; 0532
[2] Patent: US2009/203705, 2009, A1. Location in patent: Page/Page column 43
[3] Patent: WO2012/101063, 2012, A1. Location in patent: Page/Page column 143-144
[4] Patent: WO2012/101064, 2012, A1. Location in patent: Page/Page column 185
[5] Patent: WO2014/139328, 2014, A1. Location in patent: Page/Page column 403
