Process for the preparation of substituted N-(2-chloroethyl)-N'-hydroxy-3-phenoxypyridazin-3-carboxamidine and substituted 3-(3-phenoxy-pyridazin-4-yl)-5,6-dihydro-4H-1,2,4-oxadiazine

By employing an improved preparation method that utilizes the direct reaction of a chlorinating agent and hydroxylamine, the problems of low yield and safety risks in existing technologies have been solved, achieving efficient and safe compound preparation suitable for scale-up production.

CN122122132APending Publication Date: 2026-05-29BAYER AG
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-10-30
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing methods for preparing substituted N-(2-chloroethyl)-N'-hydroxy-3-phenoxypyridazine-3-formamidinium suffer from low yields, use of hazardous oxidants and toxic reagents, and safety risks at scale-up levels, making it difficult to achieve efficient and safe compound preparation.

Method used

The reaction of the amide with a chlorinating agent in the presence of a suitable base to generate a compound, followed by direct treatment with hydroxylamine, avoids the use of phosphorus pentachloride and large amounts of hydroxylamine. The yield is improved by steps (A) and (B), and an additional base treatment is added in step (C) to optimize the reaction.

Benefits of technology

It achieves high-yield preparation of compounds, reduces waste generation, improves reaction safety and efficiency, and is suitable for scale-up production.

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Abstract

This invention relates to a novel and improved method for preparing substituted N-(2-chloroethyl)-N'-hydroxy-3-phenoxypyridazine-3-formamidinium, which can be converted into substituted 3-(3-phenoxypyridazine-4-yl)-5,6-dihydro-4H-1,2,4-oxadiazine. Specifically, this invention relates to the preparation of 3-(3-chloro-2-fluoro-phenoxy)-N-[1-(chloromethyl)-2-(2-chloro-4-methyl-phenyl)ethyl]-N'-hydroxy-6-methylpyridazine-4-formamidinium, which can be converted into 3-[3-(3-chloro-2-fluorophenoxy)-6-methylpyridazine-4-yl]-5-(2-chloro-4-methylbenzyl)-5,6-dihydro-4H-1,2,4-oxadiazine; More specifically, it involves 3-(3-chloro-2-fluoro-phenoxy)-N-[1-(chloromethyl)-2-(2-chloro-4-methyl-phenyl)ethyl]-N'-hydroxy-6-methyl-pyridazin-4-formamidinium, which can be converted into (5S)-3-[3-(3-chloro-2-fluorophenoxy)-6-methylpyridazin-4-yl]-5-(2-chloro-4-methylbenzyl)-5,6-dihydro-4H-1,2,4-oxadiazine.
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Citation Information

Patent Citations

  • Method and apparatus for operating system downloads in a set-top box environment

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  • Heterocyclyl pyridazine as fungicidal compounds

    WO2020127780A1

  • 3-(pyridazin-4-YL)-5,6-dihydro-4h-1,2,4-oxadiazine derivatives as fungicides for crop protection

    WO2021255071A1