Background and overview of the preparation method of n-butylboronic acid
N-Butylboronic acid is a monosubstituted boronic acid, which is an intermediate in asymmetric synthesis and C-C bond coupling reactions. Monosubstituted boric acid can be prepared by a one-step reaction between butyllithium and triisopropyl borate or by a Grignard reaction from butyl bromide.
Monosubstituted boronic acids are widely used in Suzuki cross-fluoroboric acid coupling reactions. Suzuki-Miyaura coupling reaction (SMC) is an important reaction to construct various C-C single bonds, and its main raw material is organic boronic acid compounds.
Preparation method of n-butylboronic acid
Report on the preparation method of n-butylboronic acid 1.
Synthesis of butylboronic acid: Butylboronic acid was prepared on a medium scale in a 10L reactor by adding BuLi to triisopropyl borate at a temperature of -42 to -50°C to obtain 197g (76 %). Vmax is 6.5L (32.5L/kg).
Preparation method report 2 of n-butylboronic acid
In a 100 mL single-neck round flat-bottomed flask, add 10 mmol of trisubstituted borate ester, 10 mmol of bromobutane, 12 mmol of magnesium powder, 50 mL of tetrahydrofuran dried with potassium hydroxide and a little iodine, install a reflux condenser, and place under ultrasonic wave Adjust different temperatures in the reactor and conduct ultrasonic radiation for 30 minutes. After the reaction is completed, use 2mol/L hydrochloric acid to adjust the reaction solution to be slightly acidic. After stirring for a while, separate the organic layer and a white precipitate will precipitate. Use 30mL of sodium bicarbonate for the water layer. Extract with diethyl ether twice, wash the combined organic layers with water, dry and rotary evaporate to remove the solvent to obtain a crude product. The crude product is purified by recrystallization with water. The obtained compound is measured by IR and 1H NMR spectra.
References
[1][Chinese invention] CN201880074452.0 Compounds and synthesis methods for preparing retinoid X receptor-specific retinoids
[2] Zheng Honglian, Feng Liheng. Research on ultrasonic radiation synthesis of monosubstituted boric acids[J]. Journal of Shanxi University (Natural Science Edition), 2006(04):391-393.
