Preparation method of topramezone

Abstract

The invention discloses a preparation method of topramezone. The invention aims to solve the problems of high reagent cost, high risk, high toxicity, harsh reaction conditions, tedious post-treatment and the like in the prior art. According to the technical scheme, a compound A (3-(3-halo-2-methyl-6-methylsulfonyl phenyl)-4, 5-dihydroisoxazole) and 1-methyl-5-hydroxypyrazole react in the presence of cyanide, copper salt, a ligand and an organic solvent, after the reaction is finished, an aqueous solution of a cyanide quenching agent is used for quenching the reaction, and a compound B is obtained; a reaction solution containing the topramezone is obtained. According to the preparation method, topramezone can be prepared through a one-pot method, raw materials are low in price and easy to purchase, high-pressure carbon monoxide does not need to participate in the reaction, the production safety risk is reduced, the whole reaction aftertreatment operation is simple, the reaction time is short, byproducts are few, the yield is high, three wastes are controllable, and the requirement of industrial production can be met.

Description

technical field [0001] The invention relates to the field of pesticide fungicides, in particular to a preparation method of fenfentrazone. Background technique [0002] Topramezone, ) is a 4-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide developed by BASF in Germany, which has excellent control effects on various types of grass or broad-leaved weeds, and is effective on almost all corn varieties All exhibit extremely high selectivity and are the best among the new generation of selective herbicides. At this stage, the production and preparation of fenflumezone still continues the original research synthesis process of BASF Company. Analyzing the two synthesis processes reported by it, it is not difficult to find that the production and raw material costs of fenflumezone are relatively high, exceeding 1.8 million per ton. Moreover, the entire synthesis process involves a variety of high-risk, high-temperature, high-pressure, and toxic and highly corrosive gas react...

AI Technical Summary

Problems solved by technology

These reported methods all require long reaction steps, poor atom economy, more by-products, low reaction yield, use of strong corrosive chlorination reagents and highly toxic rearrangement reagent acetone cyanohydrin, in addition, the synthesis of carboxylic acid intermediates Also need to use format reagents or flammable and explosive oxidants (such as CN112745270, CN104693195), the conditions are harsh and cannot meet the needs of industrialization

[0004] ②Using cheap metal catalysts (copper, cobalt catalysts) to replace the palladium catalyst in the original research process for carbon monoxide insertion reaction, but still unable to reduce the raw material cost of fenflumezone

The cheap metal copper catalyst strategy reported by CN113402511 requires a higher loading of catalyst and ligand. Although the price of copper salt is lower, the carbene ligand used is expensive and cannot be recycled, resulting in raw material costs in production. It is still at a high level. In addition, the carbon monoxide pressure required for this reaction to occur exceeds 20 atmospheres, which requires higher requirements for production equipment

In summary, the currently reported synthesis of fenmetrazone catalyzed by cheap metals not only cannot reduce the production cost, but also cannot avoid the harsh high-pressure carbon monoxide reaction conditions

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