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Synthetic method for 3-amino-4-fluorophenylboronic acid

A technology of fluorophenylboronic acid and a synthetic method, which is applied in the field of preparation of 3-amino-4-fluorophenylboronic acid, can solve the problems of being expensive and difficult to obtain, and achieve the effects of low cost, simple and easy operation, and high yield

Active Publication Date: 2015-04-22
DALIAN NETCHEM CHIRAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It is theoretically possible to prepare 3-amino-4-fluorophenylboronic acid from 3-amino-4-fluorophenylboronic acid pinacol ester depinacol, but in this way, there is one more step reaction, and another disadvantage of this route is PdCl 2 (dppf) expensive, not readily available

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The first step of bromination: the raw materials o-fluoronitrobenzene (367g, 2.6mol) and concentrated sulfuric acid (3057g) were stirred evenly, and N-bromosuccinimide (463g, 2.6mol) was added in batches. warm up to 70 o C reaction. The gas-phase central control reaction is completed. The reaction solution was cooled to room temperature, then poured into ice, and the product 2-fluoro-5-bromonitrobenzene was extracted with 200 ml of ethyl acetate, and evaporated to dryness to obtain a brown solid crude product. The crude product was recrystallized with petroleum ether, the GC was 98%, and the pure product was dried to obtain 198.7g, with a yield of 35.0%;

[0022] The second step reduction: mix 98% 2-fluoro-5-bromonitrobenzene (211g, 0.96mol) and iron powder (212g, 3.8mol), add 1200ml ethanol, drop glacial acetic acid (456g, 7.6 mol). Control the reaction solution with an oil bath for 60 o C reaction, take the reaction liquid and use the gas phase control re...

Embodiment 2

[0025] The first step of bromination: the raw materials o-fluoronitrobenzene (367g, 2.6mol) and concentrated sulfuric acid (2600g) were stirred evenly, and N-bromosuccinimide (463g, 2.6mol) was added in batches. warm up to 65 o C reaction. The gas-phase central control reaction is completed. The reaction solution was cooled to room temperature, then poured into ice, and the product 2-fluoro-5-bromonitrobenzene was extracted with 200 ml of ethyl acetate, and evaporated to dryness to obtain a crude brown solid. The crude product was recrystallized with petroleum ether, the GC was 98%, and the pure product was dried to obtain 227.1g, with a yield of 40.0%;

[0026] In the second step, 98% 2-fluoro-5-bromonitrobenzene (211g, 0.96mol) and iron powder (163g, 2.9mol) were mixed, 1200ml of ethanol was added, and glacial acetic acid (351g, 5.8mol) was added dropwise at room temperature. Control the reaction solution with an oil bath for 65 o C reaction, gas phase control reaction i...

Embodiment 3

[0029] The first step of bromination: the raw materials o-fluoronitrobenzene (367g, 2.6mol) and concentrated sulfuric acid (2600g) were stirred evenly, and N-bromosuccinimide (535g, 3.0mol) was added in batches. warm up to 75 o C reaction. The gas-phase central control reaction is completed. The reaction solution was cooled to room temperature, then poured into ice, and the product 2-fluoro-5-bromonitrobenzene was extracted with 200 ml of ethyl acetate, and evaporated to dryness to obtain a crude brown solid. The crude product was recrystallized with petroleum ether, the GC was 98%, and the pure product was dried to obtain 215.7g, with a yield of 38.0%;

[0030]In the second step, 98% 2-fluoro-5-bromonitrobenzene (211g, 0.96mol) and iron powder (134.4g, 2.4mol) were mixed, 1200ml of ethanol was added, and glacial acetic acid (290.4g, 4.8mol) was added dropwise at room temperature ). Control the reaction solution with an oil bath for 55 o C reaction, gas phase control reac...

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Abstract

The invention discloses a synthetic method for 3-amino-4-fluorophenylboronic acid. The method includes the steps of conducting bromination on o-fluoronitrobenzene, conducting reduction to generate 5-bromo-2-fluoroanil, making 5-bromo-2-fluoroanil and tetrahydroxydiboron react in a coupled mode to generate the product, namely, 3-amino-4-fluorophenylboronic acid. According to the method, raw materials can be easily obtained, and operation is easy and convenient. The method is an appropriate route for preparing 3-amino-4-fluorophenylboronic acid.

Description

technical field [0001] The invention relates to a preparation method of 3-amino-4-fluorophenylboronic acid. Background technique [0002] In the prior art, the synthesis method of 3-amino-4-fluorophenylboronic acid is to first nitrate p-fluorophenylboronic acid to generate 4-fluoro-3-nitrophenylboronic acid, and then use palladium carbon to catalyze hydrogenation reduction to generate 3-amino- 4-fluorophenylboronic acid (Ref: CN103626791). The problem with this synthetic route is that the nitration of p-fluorophenylboronic acid is difficult to control and the yield is unstable. The 3-amino-4-fluorophenylboronic acid pinacol ester which is the closest to the structure of 3-amino-4-fluorophenylboronic acid basically uses 2-fluoro-5-bromoaniline and pinacol diboron in PdCl 2 (dppf) prepared under catalysis. It is theoretically possible to prepare 3-amino-4-fluorophenylboronic acid from 3-amino-4-fluorophenylboronic acid pinacol ester depinacol, but in this way, there is ...

Claims

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Application Information

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IPC IPC(8): C07F5/02
CPCC07F5/025
Inventor 王宪学郑鹏
Owner DALIAN NETCHEM CHIRAL TECH
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