Studies On The Synthesis And Fungicidal Activity Of Novel Strobin Fungicide

Based on natural product methylβ-methoxyacrylates, Strobilurins were developed, which have the characteristics of high efficiency, broad spectrum, low toxicity, short residual, safety to environment and peculiar mode of action. The research on them has been a hot topic in fungicidal studies now. From the first strobilurin-type fungicide launched in 1996, 9 types of them are commercially available. It is estimated that this kind of fungicide will be the biggest fungicidal type of this year, sharing 20% of the whole fungicide market.This paper described the discovery and the recent development of strobilurin fungicides, also give a comprehensive review on the strobilurin-derivative compounds taking N-alkoxylcar-bamates as toxophore. The synthesis, mechanism and bioactivity of pyraclostrobin are studied; synthetical route, experiment method and the optimum conditions are discussed in detail, with the total yeild up to 46.2%. Based on the poison-kill group of the pyraclostrobin and the specific mode of action-inhibiting the mitochondrial electron transporation at the cytochrome bc₁ complex, using molecular design theory, introducing the pyridazinone moiety, 13 newly N-alkoxyl-N-substituted phenylcarbamates containing methylthio and oxime ether were synthesized by me too designing principles such as substructure linkage and bioisosterism. Their structures are as follows:Methyl N-methoxyl-N-2- [1-substituded-phenyl-2-methylthioethyl iminoxymethyl]phenylcarbamates: The mechanisms and process of the reactions were analyzed and discussed based on thermodynamics and kinetic principles and so on. The physical data of intermediates were listed. Pyraclostrobin and all of the title compounds were characterized by IR, ¹H NMR, MS and elemental analysis. The spectroscopic properties of these compounds were also discussed.Pyraclostrobin and title compounds were tested under 50 mg/L for fungicidal activity: pyraclostrobins had very good bioactivity, showed inhibitory ratio up to 100% against Pyricularia oryzae,Rhizoctonia solani,Botrytis cinerea and Blumeria griminis, respectively. Some title compounds exhibited high inhibitory activities, For example, compound 5e showed inhibitory ratio of 100% against Pyricularia oryzae,Rhizoctonia solani and Blumeria griminis, respectively, higher than 90.9% against Gibberella zeae.