Study On The Synthesis And Biological Activity Of Benzothiazole Derivatives

With the rapid development of science and technology, the environmental protection consciousness increases gradually. While the chemical pesticides have a great contribution to the increase of crop production, the wide use is under restrictions. In order to keep a stable increase on the crop production, it has become a focus to develop green pesticides with low toxicity, high efficiency, low resident. Benzothiazole derivatives are a kind of heterocyclic compounds with diverse biological activities, and many commercial pesticides contain this core structure. In this thesis, taking use of active substructure combination, a series of benzothiazole derivatives which contain benzothiazole and phenoxy simultaneously, are designed and synthesized. In addition, some benzothiazole derivatives with trigonal topology geometry are also synthesized. The target compounds have been confirmed by 1H NMR, 13C NMR, MS, and IR. The biological activity test reveals that a number of compounds have good activities. The main contents are as follows:1. The study strategy of new pesticides, the current state and the development perspective of herbicides, fungicides and insecticides, as well as the applications of benzothiazole derivatives in pesticide, medicine, and industry, are outlined. Meanwhile, the common strategies for the synthesis of benzothiazole derivatives are also summarized.2. Various substituted anilines were used as the raw materials to yield 2-aminobenzothiazoles.2-Aminobenzothiazoles were used for the synthesis of various 2-aminothiophenols, which reacted with phenoxy acetic acid to yield twenty-four target compounds,2-phenoxymethylbenzothiazoles. These compounds were confirmed by H NMR,13C NMR, MS, and IR.3. By taking use of the Mitsunobu reaction and 2-mercaptobenzothiazoles as the starting materials, a series of benzothiazole thioether derivatives were synthesized via the synthetic processes of deprotection, acylation and oxidation, thus ten compounds were obtained and the structures were confirmed by1H NMR, MS, and IR.4. Various substituted anilines were used as the raw materials for the synthesis of 2-(N-methylamine)benzothiazoles and 2-(N-phenylamine)benzothiazoles via a two-step procedure. These benzothiazoles reacted with phenoxyacetyl chlorides facility and five target compounds of 2-phenoxyacetylaminebenzothiazoles were obtained. The molecular structures were confirmed by1H NMR,13C NMR, MS, and IR.5. By using the Petri dish test, the herbicidal biological activities of all target compounds were tested. The results indicate that all compounds have shown some inhibitory effect against the growth of roots and stems of dicotyledon and monocotyledon.6. The bactericidal activity of some products by the Petri dish method were determined. The data showed that these compounds had some inhibitory effect against the funge Fusarium Graminearum Schw. Among which, the compound 5d showed the highest inhibitory effect, up to 65%. However, it is still inferior as compared with diniconazole.