[Synthesis]
To a solution of tetrahydrofuran (THF, 140 mL) containing 2-methoxyquinoline (10.0 g, 62.8 mmol) and triisopropyl borate (17.86 g, 95.1 mmol) was slowly added a solution of LDA (75.4 mmol) prepared from diisopropylamine (Pr'2NH) and n-butyllithium (n-BuLi) at -78 °C. The reaction mixture was stirred continuously at -78 °C for 4 h, followed by slow warming to room temperature and stirring overnight. Upon completion of the reaction, the reaction was quenched with saturated ammonium chloride (NH4Cl, 68 mL) solution and the pH was adjusted with 3 M hydrochloric acid (HCl) to 5. The organic solvents THF and hexane were removed by vacuum evaporation to give a white solid precipitate of 2-methoxyquinoline-3-boronic acid. The mixture was filtered through a Brinell funnel and the solid product was washed thoroughly with deionized water (H2O) and dried under high vacuum to give the target product (12.11 g, 95% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3), 13C NMR (400 MHz, CDCl3) and HRMS (EI).1H NMR data: δ8.64 (1H, s), 7.85 (1H, d, J=8.3 Hz), 7.80 (1H, d, J=7.9 Hz), 7.68 (1H, dd, J= 14.1,1.1Hz), 7.41 (1H, t, J=7.5Hz), 5.91 (2H, s, br), 4.18 (3H, s).13C NMR data: δ164.9,149.8,148.1,131.1,128.6,127.4,125.5,124.7,53.9.HRMS (EI) calculated values C10H10BNO3 ([M]+) 203.0754, measured value 203.0758. |