- Preparation method of 3-formyl-4-methylphenylboronic acid
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The invention discloses a preparation method of 3-formyl-4-methylphenylboronic acid. The method comprises the following steps of: adding 2-methyl-5-bromobenzaldehyde into a reaction vessel under the protection of nitrogen, adding a mixed solution of toluene and ethylene glycol, adding p-toluenesulfonic acid, carrying out heating reflux reaction, then performing desolventizing and rectifying to obtain a pure product of 2-methyl-5-bromobenzaldehyde diethyl acetal; dropwise adding tetrahydrofuran containing the pure product of 2-methyl-5-bromobenzaldehyde diethyl acetal and tributyl borate into tetrahydrofuran containing magnesium chips under the protection of nitrogen, carrying out heating reflux reaction, adding sulfuric acid to adjust the pH value to 2-4 after the reaction is finished, andperforming stirring to obtain a solution containing white solid; and adding an organic solvent into the obtained solution containing the white solid for extraction, combining all organic phases, carrying out reduced pressure rectification, recovering the solvent, and carrying out kettle bottom solid phase recrystallization to obtain the 3-formyl-4-methylphenylboronic acid. The method has the advantages of wide raw material sources, low production cost and mild reaction conditions, and is suitable for large-scale production and application.
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Paragraph 0024; 0026-0027; 0028; 0030; 0031; 0032; 0034-0035
(2020/12/15)
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- Preparation method of 3-aldehyde-4-methylphenylboronic acid
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The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of 3-aldehyde-4-methylphenylboronic acid. The preparation method comprises the following steps: with 2-methyl-5-bromobenzaldehyde as a raw material, performing a reaction on the 2-methyl-5-bromobenzaldehyde and alcohol to obtain acetal, performing a lithium halide exchange reaction on the acetal and a lithiation reagent at low temperature to obtain a phenyl lithium compound, and performing a reaction on the obtained phenyl lithium compound and a boronation reagent to obtain phenyl boronate; then hydrolyzing by using hydrochloric acid with the mass concentration of 10% to obtain crude 3-aldehyde-4-methylphenylboronic acid, and finally purifying to obtain pure 3-aldehyde-4-methylphenylboronic acid, wherein in the reaction, tetrahydrofuran is used as a reaction solvent. The preparation method of the 3-aldehyde-4-methylphenylboronic acid has the advantages as follows: used raw materials are cheap and easy to obtain, the reaction condition is mild, the posttreatment operation is simple, the production cost is relatively low, the yield is high, the reaction cost is reduced,and the preparation method is suitable for industrial production.
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Paragraph 0019; 0021-0023; 0026; 0027; 0036; 0037
(2018/07/03)
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