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Synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester

A technology of pinacol ester and alkylpyrazole, which is applied in the field of organic compound synthesis and achieves the effects of simple synthesis route, low cost of raw materials and mild reaction conditions

Active Publication Date: 2014-02-26
DALIAN NETCHEM CHIRAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The shortcoming of this method is that pinacol borane and catalyzer are relatively expensive and costly, and difficult to operate

Method used

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  • Synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester
  • Synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester
  • Synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] A method for preparing 1-alkylpyrazole-4-boronic acid pinacol ester, 1-methylpyrazole-4-boronic acid pinacol ester is an example:

[0027] The preparation of the first step 4-iodopyrazole:

[0028] The raw material pyrazole (10g) and ethanol (10g) are stirred evenly, and iodine (22.4g) is added in batches, and the temperature rises (20°C-30°C), and 30% hydrogen peroxide (16.7g) is added dropwise, and the temperature is not higher than 70 After the dropwise addition was completed and stirred for 1 hour, TLC tracked the end of the reaction, added 10 g of saturated aqueous sodium bisulfite solution, stirred for 1 hour, filtered to obtain a white solid, washed the filter cake with 20 g of water, concentrated the filtrate, and solids were precipitated, re-filtered and washed, combined and filtered The cake was dried, weighing 25.7g, GC purity: 99%, yield 90%;

[0029] The preparation of second step 1-methyl-4-iodopyrazole:

[0030] Stir 4-iodopyrazole (20g) and ethanol (10...

Embodiment 2

[0034] A method for preparing 1-alkylpyrazole-4-boronic acid pinacol ester, 1-methylpyrazole-4-boronic acid pinacol ester is an example:

[0035] The preparation of the first step 4-iodopyrazole:

[0036] The raw material pyrazole (10g) and ethanol (10g) are stirred evenly, and iodine (22.4g) is added in batches, there is a phenomenon of temperature rise (20°C-30°C), and hydrogen peroxide (16.7g) is added dropwise, and the temperature is controlled not to exceed 70°C , the dropwise addition was completed and stirred for 1 hour, followed by TLC for the completion of the reaction, adding 10 g of saturated aqueous sodium bisulfite solution, stirring for 1 hour, filtering to obtain a white solid, washing the filter cake with 20 g of water, concentrating the filtrate, and solids were precipitated, re-filtering and washing, and combining the filter cake Drying, weighing 25.7g, GC purity: 99%, yield 90%;

[0037] The preparation of second step 1-methyl-4-iodopyrazole:

[0038] Stir...

Embodiment 3

[0043] A method for preparing 1-alkylpyrazole-4-boronic acid pinacol ester, 1-isopropylpyrazole-4-boronic acid pinacol ester is an example:

[0044] The preparation of the first step 4-iodopyrazole:

[0045] The raw material pyrazole (10g) and ethanol (10g) are stirred evenly, and iodine (18.6g) is added in batches, and the temperature rises (20°C-30°C), and 30% hydrogen peroxide (16.7g) is added dropwise, and the temperature is controlled not to exceed 70 degrees, stirring for 1 hour after the dropwise addition, TLC tracking the end of the reaction, adding 10g of saturated sodium bisulfite aqueous solution, stirring for 1 hour, filtering to obtain a white solid, washing the filter cake with 20g of water, concentrating the filtrate, solids precipitated, re-filtering and washing, and combining Filter cake was dried, weighed 22.8g, GC purity: 99%, yield 80%;

[0046] The preparation of second step 1-isopropyl-4-iodopyrazole:

[0047] Sodium hydride (16.5g) was dispersed in 90m...

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Abstract

The invention belongs to the field of organic chemical synthesis and provides a synthetic method of 1-alkylpyrazole-4-boronic acid pinacol ester. The synthetic method comprises the following three steps: 1. reacting pyrazole with iodine and hydrogen peroxide to generate 4-iodopyrazole A; 2. reacting the 4-iodopyrazole with alkyl halide to obtain an intermediate B; 3. preparing a Grignard reagent of the raw material by using 1-alkyl-4-iodopyrazole as a raw material and adopting an isopropyl Grignard reagent exchange method at 0-30 DEG C, with BE001 as a boron reagent, and reacting to obtain the final product. The technological method is accessible in raw materials, simple and convenient to operate and lower in cost and is a proper method for preparing 1-alkylpyrazole-4-boronic acid pinacol ester compounds.

Description

[0001] Technical field: [0002] The invention belongs to the field of organic compound synthesis, and relates to a preparation method of 1-alkylpyrazole-4-boronic acid pinacol ester. [0003] Background technique: [0004] 1-Alkylpyrazole-4-boronic acid pinacol ester is a relatively new class of compounds and important pharmaceutical intermediates, with broad application prospects. At present, there are two kinds of synthetic methods about this type of compound reported in the literature. Method 1: using 1-alkyl-4-bromopyrazole as the starting material, and n-butyllithium at -90 o C reaction for 1 hour, warming up to -70 o C, adding trimethyl borate, reacting for 0.5 hours, quenching with ammonium chloride aqueous solution, separating the oil phase, and concentrating to obtain 1-ethylpyrazole-4-boronic acid (Ref: Journal of Heterocyclic Chemistry; vol. 41; p. 931-940), and then esterified to give the product. The synthetic route is as follows: [0005] [0006]...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F5/04
Inventor 王宪学郑鹏
Owner DALIAN NETCHEM CHIRAL TECH
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