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A method of synthesizing aminophenylboronic acid pinacol ester

A technology for synthesizing aminophenylboronic acid and aminobromobenzene, which is applied in the field of boron chemical synthesis and can solve problems such as difficult determination of purity

Active Publication Date: 2015-07-22
CANGZHOU PURUI DONGFANG SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the o-nitrophenylboronic acid obtained in the first step contains a certain proportion, which needs to be recrystallized several times before it can be removed.
At the same time, the product o-aminophenylboronic acid obtained after reduction has a certain balance with its own dimer, and the purity is not easy to determine

Method used

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  • A method of synthesizing aminophenylboronic acid pinacol ester
  • A method of synthesizing aminophenylboronic acid pinacol ester
  • A method of synthesizing aminophenylboronic acid pinacol ester

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Example 1: Synthesis of 2-bis(trimethylsilyl)aminobromobenzene (1, ortho):

[0024] Under argon protection, in a 3L three-neck flask equipped with magnetic stirring, 2-aminobromobenzene (172 g, 1.0 mol) and triethylamine (303.6 g, 3.0 mol) were added to 850 ml of anhydrous THF solvent, and the After stirring, the reaction solution was cooled to about 0°C, and then 3.0 equivalents of trimethylchlorosilane (325.9 g, 3 moles) was slowly added dropwise, and the temperature of the system rose to 30°C during the dropwise addition. Stir for 10 minutes after dropping, and then react at 40-60°C for 1-3 hours. TLC detects that the reaction is complete. The developing solvent is: n-hexane / ethyl acetate=10:1. At this time, it is the intermediate protected by the previous trimethylsilyl group.

[0025] Cool down to -10-0°C, and maintain the temperature by adding 1.5 equivalents of commercially available 3M methylmagnesium chloride tetrahydrofuran solution (500 ml, 1.5 moles), follow...

Embodiment 2

[0026] Example 2: Synthesis of 3-bis(trimethylsilyl)aminobromobenzene (1, meta):

[0027] Under nitrogen protection, in a 3L three-neck flask equipped with magnetic stirring, 3-aminobromobenzene (172 g, 1.0 mol) and diisopropylethylamine (387.7 g, 3.0 mol) were added to 850 ml of anhydrous THF solvent , start stirring, and cool the reaction liquid to about 0°C, then slowly add 3.0 equivalents of trimethylchlorosilane (325.9 g, 3 moles) dropwise, and the temperature of the system rises to 30°C during the dropwise addition. Stir for 10 minutes after dropping, and then react at 40-60°C for 1-3 hours. TLC detects that the reaction is complete. The developing solvent is: n-hexane / ethyl acetate=10:1. At this time, it is the intermediate protected by the previous trimethylsilyl group.

[0028] Cool down to -10-0°C, and maintain the temperature by adding 1.5 equivalents of a commercially available 3.2M methylmagnesium bromide 2-methyltetrahydrofuran solution (469 ml, 1.5 moles), and t...

Embodiment 3

[0029] Example 3: Synthesis of 4-bis(trimethylsilyl)aminobromobenzene (1, p-position):

[0030] Under nitrogen protection, add 4-aminobromobenzene (172 g, 1.0 mol) and triethylamine (303.6 g, 3.0 mol) into 850 ml of anhydrous THF solvent in a 3L three-necked flask equipped with magnetic stirring, and start stirring , the reaction solution was cooled to about 0°C, and then 3.0 equivalents of trimethylchlorosilane (325.9 g, 3 moles) was slowly added dropwise, and the system temperature rose to 30°C during the dropwise addition. Stir for 10 minutes after dropping, and then react at 40-60°C for 1-3 hours. TLC detects that the reaction is complete. The developing solvent is: n-hexane / ethyl acetate=10:1. At this time, it is the intermediate protected by the previous trimethylsilyl group.

[0031] Cool down to -10-0°C, and maintain the temperature by adding 1.5 equivalents of a commercially available 2M isopropylmagnesium chloride tetrahydrofuran solution (750 ml, 1.5 moles), followe...

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Abstract

The invention relates to a method of synthesizing aminophenylboronic acid pinacol ester. The method includes subjecting bromoaniline having different substitute positions to silanization protection, reacting with magnesium metal or butyl lithium, and performing boronization / deprotection / esterification to obtain a product. Raw materials and agents, which are adopted in the method, are cheap and easily available. Reaction conditions are mild. Only simple treatment is needed after a reaction in each step is finished. The method is capable of continuous operation. The total yield is 40-55%. The purity of the product is high. The method is suitable for large-scale amplification production.

Description

Technical field: [0001] The invention belongs to the technical field of boron chemical synthesis. Background technique: [0002] Aminoboronic acid pinacol ester is used as an intermediate in the synthesis of drugs and organic light-emitting materials (LEDs), and currently more emphasis is placed on the application of this type of compound. Synthesis method Due to the particularity of the amino group itself, the synthesis method is also different at different substitution positions. Compared with the ortho-position and the meta-position, there are relatively many studies on p-aminophenylboronic acid pinacol ester. [0003] The synthesis method of p-aminophenylboronic acid pinacol ester is roughly divided into: coupling method (using p-bromoaniline and diboronic acid pinacol ester / pinacol borane to obtain Suzuki coupling under palladium catalyst, Ref: Synlett , 2003, 8, 1204; Chem.Commun.2012, 48, 4719), direct lithiation / boration (by directly adding 1.3 equivalents of butyl...

Claims

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Application Information

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IPC IPC(8): C07F5/02
CPCC07F5/02
Inventor 冷延国桂迁张进余锦华
Owner CANGZHOU PURUI DONGFANG SCI & TECH
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