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Synthetic method of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester

A technology of pinacol ester and synthesis method, which is applied in the fields of compounds, chemical instruments and methods, and organic chemistry containing elements of Group 3/13 of the periodic table, and can solve the problems of inflammability and explosion, high production cost and high production cost. and other problems, to achieve the effects of reducing production costs, simple synthesis methods, and cheap raw materials

Active Publication Date: 2014-08-27
CHEN STONE GUANGZHOU CO LTD
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

This makes the production cost extremely high
And this method usually requires the use of ultra-low temperature and is not suitable for scale-up production
[0008] The second method uses dangerous butyllithium, which is flammable and explosive, and brings great safety hazards in production. It is not suitable for production scale-up, and butyllithium needs to use ultra-low temperature conditions, which greatly increases production costs.
[0009] Although these methods can all produce α-alkenylboronic acid pinacol esters, there are inevitable safety hazards in the scale-up production, or the production cost is too high

Method used

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  • Synthetic method of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester

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[0029] A kind of synthetic method of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester, comprising steps:

[0030] 1) Tetrahydropyrone reacts with hydrazine hydrate in a solvent to form a monoketone hydrazone;

[0031] 2) Monoketone hydrazone and copper bromide react in a solvent in the presence of triethylamine to obtain a dibromo intermediate;

[0032] 3) The dibromo intermediate reacts with the base in a solvent to obtain an alkenyl bromide compound;

[0033] 4) In the presence of palladium complexes, alkenyl bromide compounds and biboronic acid pinacol esters undergo a Suzuki-Miyaura reaction in a solvent to obtain the product.

[0034] In step 1), the molar ratio of tetrahydropyrone to hydrazine hydrate is 1: (1-20); preferably, it is 1: (2-5).

[0035] In step 1), the solvent is dichloromethane, dichloroethane, trichloroethane, tetrachloroethane, diphenyl ether, diethyl ether, methyl tert-butyl ether, ethylene glycol dimethyl ether, ethyl ether, One of glycol diethyl ...

Embodiment 1

[0047] Synthesis of tetrahydropyrone hydrazone

[0048] Under stirring, 5.0 L of dichloromethane, 2.5 kg of 80% hydrazine hydrate and 1.0 kg of tetrahydropyrone were added dropwise to the reaction kettle at 20-30°C. After the dropwise addition was complete, stirring was continued at this temperature for 2 hours. 2.0 L of saturated brine was added, the layers were allowed to stand, and the organic phase was concentrated to obtain 830 g of tetrahydropyrone hydrazone, with a yield of 73%.

Embodiment 2

[0050] Synthesis of 4,4-Dibromotetrahydropyran

[0051] Under the protection of nitrogen and at room temperature, 5.0 L of methanol, 12.0 kg of copper bromide and 7.5 L of triethylamine were added to the reaction kettle. After the addition was complete, the stirring was continued at room temperature for half an hour. A methanol solution containing 1.0 kg of tetrahydropyrone hydrazone (the volume of the solution is 2 L) was added dropwise into the reaction kettle, and stirring was continued for half an hour at room temperature. Add 15 L of ammonia water and 10 L of ethyl acetate, let stand for separation, and concentrate the organic phase to obtain the crude product, which is decolorized by activated carbon to obtain 1.7 kg of 4,4-dibromotetrahydropyran (purity greater than 95%), with a yield of 80 %.

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Abstract

The invention discloses a synthetic method of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester, which comprises the following steps: 1) carrying out a reaction of tetrahydro-4H-pyran-4-one and hydrazine hydrate in a solvent to generate single ketone hydrazone; 2) carrying out a reaction of the single ketone hydrazone and copper bromide in a solvent in the presence of triethylamine to obtain a dibromo intermediate; 3) carrying out an elimination reaction of the dibromo intermediate and an alkali in a solvent to obtain an alkenyl bromide compound; 4) carrying out a Suzuki-Miyaura reaction of the alkenyl bromide compound and bis(pinacolato)diboron in a solvent in the presence of a palladium complex to obtain the product. The synthetic method of the invention is simple, and low in cost, adopts no dangerous raw materials, and is safe and suitable for large-scale production.

Description

technical field [0001] The invention relates to a synthesis method of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester. Background technique [0002] In the prior art, there is no bibliographic report on the synthesis of 3,6-dihydro-2H-pyran-4-boronic acid pinacol ester. In general, the methods for synthesizing other types of α-alkenylboronic acid pinacol esters are as follows. [0003] Method 1 uses a ketone as a raw material to react with a trifluoromethanesulfonic acid compound to obtain an intermediate, and then reacts with biboronic acid pinacol ester to obtain the target product. [0004] [0005] The second method uses ketone as a raw material to react with p-toluenesulfonyl hydrazide to obtain an intermediate, and then reacts with butyl lithium and isopropyl borate pinacol ester to obtain the target product. [0006] . [0007] Method one involves the use of trifluoromethanesulfonic acid compounds, which are expensive. Four moles of trifluoromethanesulfonic...

Claims

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Application Information

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IPC IPC(8): C07F5/04
Inventor 郎丰睿戴洪果龙翔天陆永章王娟
Owner CHEN STONE GUANGZHOU CO LTD
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