Improved synthetic method of penoxsulam

A penoxsulam and synthetic method technology, applied in the direction of organic chemistry, can solve the problems of unsatisfactory results, increased content of impurities in by-products, unfavorable products, etc., and achieve safe post-processing steps, less product loss, The effect of cost reduction

Active Publication Date: 2017-08-08
SICHUAN FOURSTAR BIOTECH RANDD CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this synthesis method, moisture will be generated before the etherification synthesis and during the etherification process, and the generated moisture is not conducive to the reaction, and the content of by-product impurities will also increase, which is not conducive to obtaining the required content of the product
Therefore, satisfactory results cannot be obtained in this synthetic method, and the idea still has obvious flaws and deficiencies

Method used

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Examples

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preparation example Construction

[0040]The synthesis method of penoxsulam described in the present invention specifically relates to the improvement of the etherification step of preparing penoxsulam through etherification of tetrafluorosulfonamide. The etherification step uses strong basic substances, difluoro Ethanol and tetrafluorosulfonamide (an intermediate in the synthesis of penoxsulam, 2-fluoro-6-trifluoromethyl-N-(5,8-dimethoxy-[1,2,4]triazolo [1,5-c]pyrimidine-2)-benzenesulfonamide for short) as raw material, the specific synthesis process includes the following steps:

[0041] I, the preparation of A liquid

[0042] Under the protection of nitrogen, firstly, the strongly basic substance was dissolved in ethylene glycol dimethyl ether under ice-water bath conditions to obtain a strongly basic solution; then, difluoroethanol was added dropwise to the strongly basic solution, and passed Control the rate of addition of difluoroethanol to control the temperature of the reaction system below 10°C to pre...

example 1

[0056] In a 2000mL four-neck round bottom flask equipped with a thermometer, nitrogen balloon and rubber stopper, add 700g of ethylene glycol dimethyl ether, under the protection of nitrogen, cut 30.4g of peeled metal sodium (1.32mol, 2.2eq) into small pieces Add the block into the system, fully stir in the ice-water bath and cool down to about 5°C, slowly add 49.2g (0.6 mol, 2.0eq) of difluoroethanol to the system dropwise, pay attention to the obvious heat release during the dropping process, and a large amount of gas is generated, the reaction system The temperature is controlled below 10°C, and the drop rate of difluoroethanol is adjusted by changing the temperature. After the dropwise addition was completed, tetrafluorosulfonamide (126 g, 0.3 mol, 1.0 eq) was slowly added to the system in batches at about 10°C. The addition process is still accompanied by a large amount of gas generation and obvious exothermic phenomenon. Control the addition speed so that the system temp...

example 2

[0059] Potassium tert-butoxide is used instead of sodium metal. For a specific implementation, refer to Example 1. The product is dried, and the HPLC content determination is >98%, and the yield is 93.5%.

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Abstract

The invention discloses an improved synthetic method of penoxsulam. The improved synthetic method comprises the following steps: taking a strong-alkalinity substance, difluoroethanol and 2-fluoro-6-trifluoromethyl-N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyridine-2-yl)benzsulfamide (hereinafter to be referred as tetrafluorosulfamide) as raw materials; taking the strong-alkalinity substance and the difluoroethanol to react to prepare a solution A (in the presence of the difluoroethanol) which has relatively weak alkalinity and contains F2CH1CH2O-; adding the tetrafluorosulfamide to prepare the penoxsulam. Therefore, all the raw materials are added in sequence and the temperature of a reaction system is controlled; side reaction can be effectively reduced; the content of impurities is reduced, the purity of a product is improved or a purification step is reduced.

Description

technical field [0001] The invention relates to a synthesis method of penoxsulam, in particular to a synthesis method for improving the etherification step in the synthesis step of penoxsulam. Background technique [0002] Penoxsulam (Peoxsulam) is a sulfonamide herbicide developed by W.A. Kleschick and others from Dow AgroSciences by using the biological isosteric relationship. Its main mechanism of action is the same as the current sulfonylureas and imidazolinones, which are acetolactate synthase (ALS) inhibitors. After systematic and in-depth research, they found that 1,2,4-triazolo[1,5-a]pyrimidine ring and sulfonylurea have good bioisosteric activity. After comprehensive consideration of synthetic factors W.A. Kleschick et al successfully prepared a series of oxaziminosulfonamides after the sulfonyl group and amino group were reversed. [0003] Penoxsulam is a post-emergence herbicide that inhibits acetolactate synthase (ALS). It is mainly used for weeding in paddy f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D487/04
CPCC07D487/04
Inventor 王文吴狄峰马青伟刘修兵
Owner SICHUAN FOURSTAR BIOTECH RANDD CORP
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