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Preparation method of 3,4-dimethoxybenzyl bromide

A technology of dimethoxybenzyl and methylation, which is applied in the field of preparation of 3,4-dimethoxybenzyl bromide, can solve the problems of toxicity of triphenylphosphorus, low yield and the like, and achieves low cost, High yield and the effect of expanding production

Inactive Publication Date: 2014-05-21
江苏斯威森生物医药工程研究中心有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, there are many methods for preparing 3,4-dimethoxybenzyl bromide at home and abroad, and most of them have relatively large shortcomings, which still need to be solved
Mishra et al. (Mishra, Rajesh Kumar; Yadav Tetrahedron letters, 2002, Vol. 1, 43, p. 31, 5419-5422) reported that the starting material was mixed with carbon tetrabromide and triphenylphosphine in Reaction produces product in dichloromethane, yield 52%, and this method yield is low, and triphenylphosphine is poisonous

Method used

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  • Preparation method of 3,4-dimethoxybenzyl bromide

Examples

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Comparison scheme
Effect test

Embodiment 1

[0019] The preparation of embodiment 1 veratraldehyde

[0020] Weigh 20g of vanillin and 27.2-36.3g of potassium carbonate into a single-necked bottle equipped with a thermometer, stir in an ice bath for 30min, slowly add 10.6-12.3ml of methyl iodide dropwise, keep the temperature for 1-2h, stir at room temperature for 20-22h, and react When finished, cool to room temperature.

Embodiment 2

[0021] Example 2 Preparation of Veratrol

[0022] The above reaction solution was stirred in an ice bath for 30 minutes, and 6.0-7.5 g of sodium borohydride was slowly added in batches, and reacted at room temperature for 4-7 hours.

Embodiment 3

[0023] Embodiment 3 3, the preparation of 4-dimethoxybenzyl bromide

[0024] The above reaction solution was cooled to -5-0°C, 6.1-9.8ml of boron tribromide was added dropwise, and reacted at room temperature for 5-6 hours. After the reaction was completed, it was concentrated under reduced pressure, recrystallized from methanol, and the weight yield was 80-85%.

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PUM

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Abstract

The invention relates to a preparation method of 3,4-dimethoxybenzyl bromide, and discloses a preparation method comprising the following steps: with vanillin as a starting raw material, under inorganic weak base, reacting the vanillin with a methylation reagent to generate veratraldehyde; reacting with sodium borohydride to reduce an aldehyde group into alcohol so as to obtain veratryl alcohol; brominating with boron tribromide to obtain a final product. The preparation method is higher in yield, simple in operation, and high in purity; the yield reaches up to 85 percent.

Description

technical field [0001] The invention belongs to organic synthesis technology, in particular to a preparation method of 3,4-dimethoxybenzyl bromide. Background technique [0002] 3,4-Dimethoxybenzyl bromide is an important pharmaceutical intermediate widely used in the pharmaceutical industry for the synthesis of tetrahydropalmatine (tetrahydropalmatine). At present, 3,4-dimethoxybenzyl chloride is mainly used to synthesize tetrahydropalmatine (tetrahydropalmatine), which is easy to decompose when heated, and is not conducive to the production of downstream technical products. The development of 3,4-dimethyl The synthesis research of oxybenzyl bromide can overcome these difficulties, and is beneficial to improve the yield, etc., and the research of its synthesis method is of great significance. [0003] At present, there are many methods for preparing 3,4-dimethoxybenzyl bromide at home and abroad, and most of them have relatively large shortcomings, which need to be solved....

Claims

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Application Information

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IPC IPC(8): C07C41/22C07C43/225
CPCC07C41/22C07C41/26C07C45/64C07C43/225C07C43/23C07C47/575
Inventor 张梅彭学东赵金召黄显明
Owner 江苏斯威森生物医药工程研究中心有限公司
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