Background and overview of the preparation method of the boron ester compound 4-fluorobenzylboronic acid pinacol ester
The boron ester compound 4-fluorobenzylboronic acid pinacol ester is an important chemical raw material and is widely used in scientific research and industrial production. In scientific research, indium fluoroborate and boron ester compounds are mainly used as a type of synthetic intermediates, used in transition metal-catalyzed cross-coupling reactions to construct target compounds with complex structures. In industrial production, boron ester compounds are widely used in the fields of medicine, pesticides and materials.
Preparation method of boron ester compound 4-fluorobenzylboronic acid pinacol ester
Report on the preparation method of the boron ester compound 4-fluorobenzylboronic acid pinacol ester 1.
Synthesis of 4-fluorobenzylboronic acid pinacol ester: Add 56mg of 4-fluorophenylboronic acid (0.4mmol), trimethylsilyldiazomethane (2M n-hexane) to a 10mL reaction tube equipped with a magnet Alkane solution) 0.4 mL (0.8 mmol), add 1 mL of 1,4-dioxane to the system, plug it with a rubber stopper, and react on an electromagnetic heating stirrer at 50°C for 1 hour. Then, 94 mg (0.8 mmol) of pinacol (dissolved in 1 mL of 1,4-dioxane), 0.4 mL of tetrabutylammonium fluoride (1 M tetrahydrofuran solution) and 200 uL of water were added, and the mixture was heated on an electromagnetic heating stirrer at 50°C. Continue the reaction for 1 hour. After the reaction is completed, the organic solvent is removed using a rotary evaporator and purified by column chromatography to obtain 4-fluorobenzylboronic acid pinacol ester. The compound is a colorless liquid with a yield of 77%. Its NMR data are as follows: 1HNMR (MHz, CDCl3) δ7.14-7.10(m, 2H), 6.95-6.87(m, 2H), 2.25(s trifluoromethylbenzene Boric acid, 2H), 1.23 (s, 12H); 13CNMR (100MHz, CDCl3) δ160.8 (d, J=241.9Hz), 134.1 (d, J=3.1Hz), 130.2 (d, J=7.6Hz), 114.9 (d, J=21.2Hz), 83.5, 24.7.
Report 2 on the preparation method of the boron ester compound 4-fluorobenzylboronic acid pinacol ester,
Boron esterification reaction of p-fluorobenzyl chloride and pinacol diborate catalyzed by Fe(acac)3 under the condition of adding magnesium chips in situ. The operation is as follows: under argon protection, add catalyst (3.5 mg, 0.010 mmol, 2 mol%), pinacol diborate (127.0 mg, 0.5 mmol), and magnesium chips (16.8 mg, 0.7 mmol) in sequence. Tetrahydrofuran (1 ml), after adding p-fluorobenzyl chloride (162 μl, 1.35 mmol) at 0°C, reacted for 3 hours, added water to terminate the reaction, the reaction product was extracted with ethyl acetate, and the yield was calculated by gas chromatography to be 93 %. Dissolve the product in CDCl3 (about 0.4 mL), seal the tube, and measure and characterize on a Unity Inova-type NMR instrument at room temperature: 7.14-7.10 (m, 2H), 6.93-6.88 (m , 2H), 2.25 (s, 2H), 1.22 (s, 12H).
