A kind of synthesis technique of pyraclostrobin

Abstract

The invention concretely relates to a synthetic technology for pyraclostrobin. The synthetic technology comprises: firstly performing cyclization to obtain 1-(4-chlorophenyl)-pyrazol-3-one, oxidizing the pyrazol ring under the effect of an oxidant to generate 1-(4-chlorophenyl)-3-hydroxypyrazole, then using 2-nitrobenzyl bromide to performing etherification to generate 1-(4-chlorophenyl)-3-[2-(nitrophenyl)methoxy]-1H-pyrazole, then using a reducing agent to perform nitro reducing, so as to generate N-hydroxyl-2-[N'-(4-chlorophenyl)pyrazol-3'-yloxymethyl]aniline, then using ClCO2CH3 to perform N-acylation reaction to generate methyl N-hydroxyl-N-2-{[N'-(4-chlorophenyl)pyrazol-3'-yloxymethyl]phenyl}formate, and finally performing hydroxyl methylation under an alkaline condition to generate pyraclostrobin. The technology enables all operations in the pyraclostrobin preparation process to be relatively controllable, helps to improve the stability of the preparation process and improve the product yield, successfully employs low-cost reagents and substantially reduces production cost, and also the employed reagents are relatively small in toxicity, is relatively beneficial for environment protection, and has no corrosivity on plastic pipes, so that the production safety is improved.

Description

technical field [0001] The invention belongs to the field of preparation of original drug compounds, and in particular relates to a synthesis process of pyraclostrobin. Background technique [0002] Pyraclostrobin, chemical name: N-[2-[[[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy]methyl]phenyl]-N- Methoxy-methyl formate, the chemical structural formula is: [0003] . [0004] Pyraclostrobin is an excellent variety of methoxyacrylate fungicides with a pyrazole structure developed by BASF. Because of its high efficiency, low toxicity, stable chemical properties, and wide bactericidal spectrum, it has become a fungicide developed by domestic and foreign pesticide companies. One of the varieties. It can be widely used in various crops such as wheat, peanut, rice and fruit trees, and has a strong control effect on a wide range of diseases such as powdery mildew, sheath blight, brown spot, gray mold, and downy mildew. [0005] At present, there are two main synthetic routes for ...

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Problems solved by technology

[0007] Although this synthetic patent method can achieve the purpose of synthesizing pyraclostrobin, the disadvantages in the preparation process are: (1) The generation of hydroxylamine during the reduction process of nitro hydrogenation is difficult to control, and hydroxylamine is easy to continue hydrogenation Amines are generated; (2) Methylation with expensive methyl iodide is too expensive for industrial production; (3) Dibromide is easily generated during bromination of methyl groups, making it difficult to purify the reactants

[0010] Although this synthetic patent method can also achieve the purpose of synthesizing pyraclostrobin, it is difficult to control the formation of hydroxylamine during the hydrogenation reduction process of the nitro group in the preparation process, and hydroxylamine is easy to continue hydrogenation to generate amines. In addition to the disadvantage of high cost, tetrahydropyrrole is used to protect the bromomethyl group, and then deprotect it, the reaction route is longer

Moreover, tetrahydropyrrole has a strong taste and pollutes the environment. In addition, tetrahydropyrrole is also quite corrosive to plastic pipes.

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