Studies On Design Synthesis And Herbicidal Activity Of N-(Chloronictinic) O-substituent Aryl Sulfonamides

Acetolactate synthase (ALS EC4.1.3.18) is the first common enzyme in branched-chain amino acid synthesis in plants. It is a thiamin pyrophosphate (TTP)-dependent enzyme which catalyses the condensation of two pyruvate molecules to form acetolactate and carbon dioxide in the leucine and valine biosynthesis pathway, or the condensation of pyruvate and α-ketobutyric acid to form α-aceto-α-hydroxybutyrate and carbon dioxide as the first step in the isoleucine biosynthesis. ALS inhibitors are one of the most important classes of herbicides used for selective weed control in variety of crops. They can inhibit weeds growth or kill weeds which interfere with branched-chain amino acids by inhibiting ALS activity in plants. The attribute of low application rate, good crop selectivity, environmental safety and compatibility with the trend towards post-emergence weed control exhibited by these compounds are important characteristics for modern agrochemicals, which have led to the rapid success of ALS inhibitors as herbicidal products and attracted a world-wide research commitment. Over the past two decades, thirteen structurally diverse classes of ALS inhibitors including herbicides of sulfonylurea, imidazolinone, sulfonamide and pyrimidylsalicylate have been found, and much effort is being put into finding new classes.In this thesis, the creative processes of sulfonylurea and sulfonamide herbicides were described. The research progress of ALS, structure-activity and theoretical research of sulfonylurea and sulfonamide herbicides were also reviewed. Two series of novel sulfonamide including twelve compounds were synthesized on the base of four sulfylchoride compounds and six sulfonamide compounds. Their structures were confirmed by elemental analysis, 1H NMR and IR. Many reactions were discussed. Some experimental procedures were improved and synthetic yields were enhanced. Spectrums of compounds were analyzed.The herbicidal activity was determined to rape, cucumber and corn, and results showed that some compounds have good activity. Among of them, the activity of N-(6ˊ―chloronictinic)O-nitrophenyl sulfonamides is the best. The inhibiting activity to cucumber and corn of both compoundsⅡ1 and Ⅱ6 different concentrations was measured and their logarithmic regression formulas,LC50 and pI50 were calculated.The crystal structures of both compounds Ⅰ2 and Ⅱ2 were determined by x-ray diffraction.Ⅰ2 is monoclick structure and Ⅱ2 is triclick structure. Both of them have three different plane—ester plane(Ⅰ),benzyl plane(Ⅱ), chloroniccotinic plane(Ⅲ). Their herbicidal activity were discussed and compared with herbicides of similar structure.