The Study On A New Procedure For Synthesis Of Silthiopham And The New Active Compounds Against Gaeumannomyces Graminis Var.tritici.

The Take-all disease of wheat is an incurable fungus disease spreading through the soil.It occurs on wheat's root or base and there is a trend to develop in our country.At present chemical control is the main measure to control take-all disease.Silthiopham is a unique fungicide developed overseas to prevent take-all disease of wheat efficiently,but the cost of silthiopham is very high because of harsh conditions,patent protection and the unavailable raw material.These problems restrict the application of the product seriously.To solve the above problems,we develop a new procedure for synthesis of silthiopham and design the new active compounds against Gaeumannomyces graminis var.tritici.1.The new procedure for synthesis of silthiopham was developed.According to the features including harsh conditions and the unavailable raw material,a new procedure was designned using methyl propiolate and 3-mercapto-2-butanone as starting materials.Firstly,methyl propiolate reacts with chlorotrimethylsilane in the presence of Et3 N to get methyl 3-(trimethylsilyl)propiolate.Then,3-(trimethylsilyl)propiolate cyclizates directly with 3-mercapto-2-butanone promoted by CH3 ONa to get methyl 4,5-Dimethyl-2-trimethylsilyl-thiophene-3-carboxylate.The third,methyl 4,5-Dimethyl-2-trimethylsilylthiophene-3-carboxylate is hydrolyzed selectively to afford 4,5-dimethyl-2-(trimethylsilyl)thiophene-3-carboxylic acid.Finally,the silthiopham is obtained by the amination of 4,5-dimethyl-2-(trimethylsilyl)-thiophene-3-carboxylic acid.The new procedure has many advantages compared with previous route,such as available raw materials,the mild reaction conditions,high yield at single step and high purity of the final product.So it is favorable for the large-scale production and make it a broad application prospect.2.In order to understand the relationship between thiophene carboxamides structure and its activity,we designned more than 30 thiophene carboxamides and thiophenecarbonyl thiourea derivatives to get the alternative active lead compounds against Take-all disease of wheat.The structures of the compounds were confirmed by 1H NMR,13 C NMR and elemental analysis.The activities of these compounds against Gaeumannomyces graminis var tritici were evaluated in vitro.It was found that nine new compounds on Gaeumannomyces graminis var.tritici show excellent antibacterial activity,two of which are even better than silthiopham.According to the results of the test,the relationship between thiophene carboxamides' structure and its antibacterial activity is analyzed,which provides a certain theoretical support for the development of new fungicides lead compounds.