Synthesis And Biological Activity Of Benzothiazole Sulfonamides And Phosphonates

Weeds are one of the main causes of crop reduction. Since human beings farming,struggling with weeds has never brought to an end, just as the so-called "not burned out by wild fire but brought to growth with spring breeze." Along with the advent and large-scale applications of herbicides, it brought the gospel to agriculture, not only greatly .reduces the reduction caused by weeds, but also improve the efficiency of weeding, save labor and promote the modernization of agriculture. The development of ultra-efficient, low toxicity, environmentally friendly new herbicide is the focus of the new pesticide research. Benzothiazole is core structure of many pesticides with, and many highly efficient pesticides contain this heterocyclic structure. In this paper, a series of salicylamide sulfonates containing benzothiazole heterocycles and (6-substituted benzothiazol-2-yl)(hydroxy) methylphosphonates were designed and synthesized with the strategy of active substructure splicing method. The target compounds were characterized by 1H NMR, 12C NMR, MS and FTIR, at the same time, their herbicidal activity was tested. The details of this thesis are as follows:1. The synthetic methods of the new active compound are summarized, and the research progress of amide compounds, phosphonate esters and heterocyclic herbicides were briefly introduced.2. The raw material 4-substituted aniline reacted with ammonium thiocyanate to produce 2-amino-6-substituted benzothiazole compounds. Then the product was amidated to generate 5-substituted-2-hydroxy-N-(6-substituted benzo[D]thiazol-2-yl)benzamide compounds by 2-hydroxy-5-substituted salicylic acid compound. Finally it happened nucleophilic substitution reaction with aliphatic hydrocarbons (or aromatic hydrocarbons) sulfonyl chloride and formed 44 heterocyclic salicylamide sulfonate target compounds. The reaction conditions of each step in the route were systematically studied.3. The 2-amino-6-substituted benzothiazole was used as the starting material to react with isoamyl nitrite first to give 6-substituted benzo[d]thiazole; Then reacted with n-butyllithium (n-BuLi), N, N-dimethylformamide (DMF) under anhydrous anaerobic conditions to give 2-carbaldehyde-6-substituted benzo[d]thiazole. Finally it reacted with the phosphonate compound to produce 20 (6-substituted benzothiazol-2-yl)(hydroxy)methylphosphonate target compound.The conditions of anhydrous anaerobic reaction in the route were studied.4. We adopt indoor petri dish method to test the herbicidal activity of the target compounds 6, 9 and 13 preliminarily. The results showed that they had certain inhibitory activity on the roots and stems of the dicotyledonous plants-rapeseed and monocotyledonous-barnyard grass. When the concentration is high, the inhibitory activity of some compounds can reach to the ?-? level. When the concentration is decreased, the inhibitory activity of the compounds is also decreased, which is basically in the ?-? range. Among them, the inhibitory effect of compound 13 on the roots of dicotyledonous plants was similar to that of 2,4-D,which is a selective inhibitor of the roots of dicotyledonous plants.