Method for synthesizing 6-amino-7-fluorine-2H-1, 4-benzoxazine-3-(4H)-ketone

Abstract

The invention discloses a method for synthesizing 6-amino-7-fluorine-2H-1, 4-benzoxazine-3-(4H)-ketone. 2, 4, 5-trichlorine-nitrobenzene serves as a raw material, the 2, 4, 5-trichlorine-nitrobenzeneand fluorinating agent are subjected to fluorination reaction to obtain 2, 4-difluoro-5-chlorine-nitrobenzene, the 2, 4-difluoro-5-chlorine-nitrobenzene and hydroxy acetate are subjected to etherification reaction to obtain 2-(5-fluorine-4-chlorine-2-nitrophenoxy) acetate, the 2-(5-fluorine-4-chlorine-2-nitrophenoxy) acetate and sodium amide react to obtain 2-(5-fluorine-4-amido-2-nitrophenoxy) acetate, and the 2-(5-fluorine-4-amido-2-nitrophenoxy) acetate is catalyzed, hydrogenated and reduced to obtain 7-fluorine-6-amino-2H-1, 4-benzoxazine-3-(4H)-ketone. Reaction technological conditions inall steps are mild, operation is simple and convenient, the method is high in safety and short in reaction time, and industrial production can be popularized.

Description

Technical field [0001] The invention relates to the technical field of herbicide production and preparation, in particular to a method for synthesizing 6-amino-7-fluoro-2H-1,4-benzoxazine-3-(4H)-one Background technique [0002] 6-Amino-7-fluoro-2H-1,4-benzoxazine-3-(4H)-one is a kind of pesticide intermediate, which can be used to synthesize the herbicide flumiacet, which is the original Porphyrinogen oxidase (PPO) inhibitor, used to control weeds and broadleaf weeds on soybeans, cotton, grapes and many other crops, 6-amino-7-fluoro-2H-1,4-benzoxazine- The chemical structure of 3-(4H)-ketone is as follows: [0003] [0004] Among the various synthesis technologies that have been published, there is a precursor of 2-(5-fluoro-2,4-dinitrophenoxy) through nitration, fluorination, etherification and other steps using m-dichlorobenzene as a raw material. Acetate, when fluorinated from dichloromethane to difluoride, the amount of tar is large, the product loss is large, and etherifica...

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Problems solved by technology

[0004] Among the various synthetic techniques that have been published so far, there are m-dichlorobenzene as raw materials, and the precursor 2-(5-fluoro-2,4-dinitrophenoxy) is obtained through nitration, fluorination, etherification and other steps. Acetate, when dichlorofluorinated to difluoro, the amount of tar is large, the product loss is large, etherification will produce impurities that both fluorines are etherified

There is 2,4-difluoronitrobenzene as the raw material, which undergoes hydrolysis, etherification, reduction, nitration, and reduction. Although the raw material is easy to obtain in this route, the route is long and the impurities are high. At the same time, hydrogenation is required twice, and the cost is increased. , cumbersome operation

There is m-fluorophenol as the starting material, although the reaction route is not very long, but the raw material is rare and expensive, the nitration reaction conditions are severe, the ether bond is easy to break, the impurities are high, and the product yield is low

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