2,6-diethyl-4-methylphenylboronic acid synthesis

Yield:953075-90-6 82.2%

Reaction Conditions:

Stage #1: 1-bromo-2,6-diethyl-4-methylbenzenewith n-butyllithium in tetrahydrofuran;hexane at -65; for 0.5 h;Inert atmosphere;
Stage #2: Trimethyl borate in tetrahydrofuran;hexane at -65; for 0.5 h;Inert atmosphere;

Steps:

1-3 Example 3:

In a 1000mL dry four-neck flask, vacuumize and replace the system with nitrogen three times, Then under the protection of nitrogen, add 200mL of anhydrous tetrahydrofuran, 40g 2,6-Diethyl-4-methylbromobenzene (molecular weight 227.15, 176.1mmol, 1eq), The temperature of the dry ice acetone bath was lowered to -65°C, and 105.6 mL of n-butyl lithium n-hexane solution (2.5 mol/L, 264.1 mmol, 1.5 eq) was slowly added dropwise. After dripping in about 50min, After dripping, continue stirring at -65°C for 0.5h. Then slowly add 36.60g dropwise Borane trimethyl ester (molecular weight 103.91, 352.2mmol, 2.0eq), After dripping for about 45 minutes, continue to stir at -65° C. for 0.5 h after dripping, and then let the dry ice acetone bath evaporate naturally to raise the temperature of the reaction solution to room temperature and stir overnight. Add 150mL 1mol/L The reaction solution was quenched with dilute hydrochloric acid of 5%, and then extracted twice with 100 mL of ethyl acetate. The combined organic phases are concentrated to dryness to obtain a crude product, which is beaten with n-hexane, Obtained 27.8g (molecular weight 192.07, theoretically 33.82g) white solid, That is 2,6-diethyl-4-methylphenylboronic acid with a mass yield of 82.2%.

References:

CN113121341,2021,A Location in patent:Paragraph 0034-0035; 0037-0038; 0041-0042