Pyroxasulfone synthesis method

A synthesis method and a technology for sulfofenazone are applied in the field of organic synthesis, and can solve the problems of increased product cost, production safety, unpleasant smell of compounds and the like

Active Publication Date: 2020-07-10
HEFEI JIUYI AGRI DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] This method uses relatively dangerous isobutylene gas when preparing dihydroisoxazole intermediates, which will cause potential safety hazards in large-scale industrial production; the halogenation step uses relatively expensive reagents NBS or NCS, which will increase p

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preparation example Construction

[0031] The invention provides a kind of synthetic method of pyrazafen, comprising the following steps:

[0032] Using compound I as the starting material, the intermediate II is synthesized through a cyclization reaction, and the intermediate II is subjected to a chlorination reaction under the action of a chlorinating agent to obtain the intermediate III; the intermediate III is reacted with thiourea to obtain the salt Salt intermediate IV;

[0033] The chlorination reagent is phosphorus pentachloride and / or phosphorus oxychloride;

[0034] The hydrochloride intermediate IV, compound VI react with formaldehyde to obtain intermediate VII, and the intermediate VII undergoes a difluoromethoxylation reaction under the condition of a catalyst to obtain intermediate VIII, and finally use hydrogen peroxide to treat The intermediate VIII is oxidized to obtain pyroxazole IX;

[0035] Described catalyst is sodium tungstate and acid;

[0036] The synthetic route among the present inv...

Embodiment 1

[0079] (1) Synthesis of compound II

[0080] Under the condition of nitrogen protection, 83.6 g (1.1 mol) of hydroxyurea was added into 500 mL methanol solution (2.4 mol / L) of potassium methoxide, and then stirred and dissolved at 25°C. At the same temperature, 128 g (1 mol) of ethyl 3,3-dimethacrylate was added dropwise for half an hour. Then it was stirred at 25°C for 18 hours. After the reaction was completed, the reaction solution was filtered to obtain a white solid, which was then dissolved in water and neutralized by adding 100 mL of hydrochloric acid (35%, 1.2 mol). Finally, it was extracted three times with 200 mL of 1,2-dichloroethane, the organic phases were combined, dried, and the solvent was distilled off under reduced pressure to obtain 91 g of a white solid with a yield of 80%.

[0081] (2) Synthesis of compound III

[0082] At 25°C, under nitrogen protection conditions, 99.5g of phosphorus pentachloride (0.48mol) was dissolved in 100mL of 1,2-dichloroethane...

Embodiment 2

[0095] Step (2) The synthesis of compound III was carried out according to the following steps, and the rest of the steps were carried out according to the method in Example 1.

[0096] (2) Synthesis of compound III

[0097] At 25°C, under nitrogen protection, 50g of phosphorus pentachloride (0.24mol) was dissolved in 100mL of toluene, compound II (25g, 0.22mol) was added to the solution in batches, and stirred at 25°C for 5 Hours. Control the reaction in the liquid phase. After the reaction, the reaction liquid was distilled under reduced pressure to obtain a yellow liquid, and then the liquid was poured into 100 mL of water, extracted 3 times with 150 mL of dichloroethane, the organic phase was collected, and the solvent was removed by distillation under reduced pressure. Obtained 20 g of light yellow liquid, yield: 68%.

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Abstract

The invention provides a pyroxasulfone synthesis method. The method comprises the steps of: adopting a compound I as a starting raw material, carrying out cyclization reaction to synthesize an intermediate II, and carrying out chlorination reaction on the intermediate II under the action of a chlorination reagent to obtain an intermediate III; reacting the intermediate III with thiourea to obtaina hydrochloride intermediate IV, wherein the chlorination reagent is phosphorus pentachloride and/or phosphorus oxychloride; reacting the hydrochloride intermediate IV and a compound VI with formaldehyde to obtain an intermediate VII, carrying out difluoromethoxylation reaction on the intermediate VII to obtain an intermediate VIII, and oxidizing the intermediate VIII with hydrogen peroxide in thepresence of a catalyst to obtain pyroxasulfone IX, wherein the catalyst is sodium tungstate and acid. According to the method, the total yield is increased to 31-38%, the raw materials are simple andeasily available, the reaction process is simple and safe, the yield is high, and the method has certain significance for industrial production.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, in particular to a synthetic method of pyrazafen. Background technique [0002] The English name of pyroxazole is Pyroxasulfone, and its chemical name is [3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylsulfonyl] -4,5-dihydro-5,5-dimethyl-1,2-oxazole], the chemical formula structure is shown below. [0003] [0004] Metrafenazole is a pre-emergent soil treatment agent developed by Japan Combination Chemicals Co., Ltd. that can be used in most crop fields. Its mechanism of action is similar to that of acetochlor and its related herbicides. Absorption, inhibition of early growth of seedlings, destruction of meristems and coleoptiles, is a serious potential inhibitor of VLCFA (very long side chain fatty acid) biosynthesis in plants. However, it can be applied to a wide variety of crops, and its biological activity is much greater than that of acetochlor and metolac...

Claims

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Application Information

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IPC IPC(8): C07D413/12
CPCC07D413/12
Inventor 祝玉超
Owner HEFEI JIUYI AGRI DEV
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