3-Methoxyphenylboronic acid

2398-37-0

121-43-7

10365-98-7

Phase I: Synthesis of 3-methoxyphenylboronic acid 1. 41.3 g (220 mmol) of m-bromoanisole was dissolved in 880 mL of tetrahydrofuran under nitrogen protection and the solution was cooled to -70 °C in an ethanol/dry ice cooling bath. 2. 160 mL (250 mmol) of butyllithium solution (1.6 M in hexane) was added slowly dropwise, with the rate of acceleration of the drop being controlled to ensure that the reaction temperature did not exceed -60 °C. 3. After stirring the reaction mixture continuously for 1.5 hours at -70 °C, slowly add 75 mL (660 mmol) of trimethyl borate dropwise, again controlling the temperature to not exceed -60 °C. 4. 4. After the dropwise addition, the reaction mixture was continued to be stirred for 1 hour under cooling conditions. 5. The reaction mixture was slowly warmed to 25 °C over a period of 2 hours, followed by the addition of 720 mL of 1 M hydrochloric acid and stirring at 25 °C for 15 hours. 6. Upon completion of the reaction, post-treatment was performed: the reaction mixture was extracted with 300 mL of ether, repeated three times, and the organic phases were combined. 7. The combined organic phases were washed sequentially with 100 mL of water and saturated sodium chloride solution, then dried with anhydrous magnesium sulfate and filtered. 8. The filtrate was concentrated on a rotary evaporator (pressure controlled at 500-10 mbar) to give 30.8 g of 3-methoxyphenylboronic acid in 92.1% yield of the theoretical value.