Synthesis
2-Benzyloxy-5-chlorophenyl iodide (5 g, 0.0145 mol) was used as a raw material in a solvent mixture of ether/tetrahydrofuran (100:30) and cooled to 0 °C to -100 °C. Under nitrogen protection, n-butyllithium (1.6 M hexane solution, 10 mL, 0.016 mol) was added slowly and dropwise over 15 min. Subsequently, the reaction mixture was warmed to -70 °C and kept for 1 hour. Continuing under nitrogen protection, triethyl borate (9 mL, 0.03 mol) was added dropwise. The cooling bath was removed and the reaction mixture was allowed to stir overnight at room temperature. Upon completion of the reaction, the reaction was quenched with 2N hydrochloric acid (40mL) and stirred vigorously for 1 hour at room temperature. The product was extracted with ethyl acetate, dried over magnesium sulfate and the solvent was evaporated to obtain the oil. Finally, the target product 2-benzyloxy-5-chlorophenylboronic acid (2.8 g, 74% yield) was purified by a Biotage purification system (90 g column) using ether/isohexane (50:50) as eluent.
References
[1] Patent: WO2003/84917, 2003, A1. Location in patent: Page/Page column 25
[2] Patent: WO2005/37786, 2005, A1. Location in patent: Page/Page column 41
[3] Patent: WO2004/39753, 2004, A2. Location in patent: Page 49-50
[4] Bioorganic and Medicinal Chemistry Letters, 2006, vol. 16, # 10, p. 2666 - 2671
[5] Patent: WO2005/37794, 2005, A1. Location in patent: Page/Page column 26
