3-Quinolineboronic acid

5332-24-1

191162-39-7

General procedure for the synthesis of quinoline-3-boronic acid from 3-bromoquinoline: triisopropyl borate (3.30 mL, 29.06 mmol) and 3-bromoquinoline (3.00 g, 14.49 mmol) were added to a 250 mL two-necked round-bottomed flask under nitrogen protection and dissolved in anhydrous tetrahydrofuran (100 mL). The reaction system was cooled to -78 °C and a 2M hexane solution of n-butyllithium (14.50 mL, 29.00 mmol) was slowly added dropwise through a dropping funnel over a controlled period of 1 hour. After the dropwise addition, the reaction was kept at -78 °C for 2 hours. Subsequently, the acetone/dry ice bath was removed and the reaction system was slowly warmed to 0 °C. The reaction was quenched with 2 M hydrochloric acid solution, followed by adjusting the pH with 2 M sodium bicarbonate solution to 7. The reaction mixture was extracted with ethyl acetate (3 x 100 mL). The organic phases were combined, dried over anhydrous magnesium sulfate and concentrated to dryness under reduced pressure. The product was precipitated by addition of hexane to give a white solid in 80% yield.