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Preparation method of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester

A technology of dimethoxytoluene and biboronic acid pinacol ester, which is applied in 3 fields, can solve the problems of cumbersome operation steps and high synthesis cost, and achieve the effects of good selectivity, low synthesis cost and high yield

Inactive Publication Date: 2017-05-31
NORTHWEST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The traditional method for preparing 3,4-dimethoxy-5-methylbenzeneboronic acid pinacol ester needs to first halogenate the aromatic substrate, and then prepare the aryl halide into lithium reagent or Grignard reagent to react with borate ester, Or borylation of aryl halides under palladium catalyzed conditions, the operation steps are relatively cumbersome and the synthesis cost is high

Method used

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  • Preparation method of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester
  • Preparation method of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester
  • Preparation method of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester

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Embodiment 1

[0034] Under nitrogen protection, (1,5-cyclooctadiene) (methoxy) iridium (I) dimer (20mg, 0.03mmol), 2,2'-bipyridine (9.37mg , 0.06mmol), biboronic acid pinacol ester (2.35g, 9.26mmol), then add 15mL tetrahydrofuran, stir at room temperature for 10min, the reaction system becomes dark green, then add 2,3-dimethoxytoluene (1.88g, 12.35mmol), the temperature was raised to 70°C, and the reaction was refluxed for 8h. After the reaction was complete, it was concentrated and spin-dried, and separated by silica gel column to obtain 3,4-dimethoxy-5-methylphenylboronic acid pinacol ester (2.23 g, 65%).

Embodiment 2

[0036] Under nitrogen protection, (1,5-cyclooctadiene) (methoxy) iridium (I) dimer (21mg, 0.03mmol), 4,4'-di-tert-butyl- 2,2'-bipyridine (16mg, 0.06mmol), biboronic acid pinacol ester (2.35g, 9.26mmol), then add 15mL of n-hexane, stir at room temperature for 30min, the reaction system turns dark green, then add 2, 3-Dimethoxytoluene (1.88g, 12.35mmol) was heated up to 75°C and refluxed for 6h. After the reaction was complete, it was concentrated and spin-dried, and separated by silica gel column to obtain 3,4-dimethoxy-5-methylphenylboronic acid pinacol ester (1.85 g, 54%).

Embodiment 3

[0038] Under nitrogen protection, (1,5-cyclooctadiene) iridium(I) chloride dimer (20mg, 0.03mmol), 1,10-phenanthroline (16mg, 0.06mmol) were added to a 25mL two-necked flask ), biboronic acid pinacol ester (2.35g, 9.26mmol), then add 15mL cyclopentyl methyl ether, stir at room temperature for 1h, the reaction system becomes dark green, then add 2,3-dimethoxytoluene (1.88g , 12.35mmol), heated to 120°C, and refluxed for 7h. After the reaction was complete, it was concentrated and spin-dried, and separated by silica gel column to obtain 3,4-dimethoxy-5-methylphenylboronic acid pinacol ester (2.33 g, 68%).

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Abstract

The invention discloses a preparation method of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester. The method is achieved through the following steps that 1, an iridium reagent, a ligand and bis(pinacolato)diboron are dissolved in a solvent, stirring is conducted to be dark green, and an intermediate product is obtained; 2, 1,2-dimethoxy-3-methylbenzene is added into the intermediate product, a heating reflux reaction is conducted for 6-9 h, and a coarse product of a target object is obtained; 3, the coarse product of 3,4-dimethoxy-5-methylphenylboronicacidpinacolester is subjected to concentration and spin dry, and 3,4-dimethoxy-5-methylphenylboronicacidpinacolester is obtained through chromatogram column separation. Accordingly, 1,2-dimethoxy-3-methylbenzene and bis(pinacolato)diboron which are easily obtained in commerce serve as starting materials to synthesize 3,4-dimethoxy-5-methylphenylboronicacidpinacolester, the preparation method is simple, separation is convenient, the yield is high, the selectivity is good, and the applied reagent is a common reagent which is low in price and easy to obtain.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and relates to a preparation method of 3,4-dimethoxy-5-methylphenylboronic acid pinacol ester. Background technique [0002] Aryl pinacol ester compounds are important intermediates in organic synthesis and are widely used in the fields of pharmaceutical synthesis and basic scientific research. For example, it is used in the synthesis of topoisomerase II inhibitor PF-03941275, AMPA receptor potentiator LY451395, non-peptide growth hormone secretagogue SM-130686, a bradykinin antagonist developed by Merck Aryl pinacol esters. [0003] [0004] [0005] 3,4-dimethoxy-5-methylphenylboronic acid pinacol ester, as a novel boronate synthetic building block, can provide a novel structure for the development of new drugs, and will It has been used in the synthesis of structural natural products. The traditional method for preparing 3,4-dimethoxy-5-methylbenzeneboronic acid pinacol est...

Claims

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Application Information

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IPC IPC(8): C07F5/02
CPCC07F5/025
Inventor 胡向东房显赫张玄
Owner NORTHWEST UNIV