| Chemical pesticides have contributed a lot to solve the food problem in the world, which would also dominate the market of pesticides in the foreseeable future. However, the efficiency of many commercial pesticides has variably decreased due to the long and broad use of a single pesticide or several pesticides with the same modes of action, which has brought a great loss for agriculture. To satisfy the increasing agricultural production needs, it's highly desirable to develop new pesticides with novel skeletons or new target sites.Recently, it's an important trend for the development of new pesticides with natural products as lead compounds. For example, fungicides with pyrrole or acrylic ester skeletons have unique modes of action, high bioactivity and no cross resistance with currently used fungicides. Considering the broad bioactivity of Sclerotiorin derivatives and their potential as fungicides, herein, we would like to synthesize a series of Sclerotiorin derivatives with highly fungicidal activity through structure modification.1. This thesis has systematically summarized the structures, synthesis and bioactivities of azaphilone and Sclerotiorin derivatives.2. We have designed and synthesized 6 different types and 129 new Sclerotiorin derivatives. All of them have been characterized by 1H NMR and HRMS, and some of them were confirmed by x-ray crystal structures. 3. In this thesis, we began with the structural modification for C-3 site with Sclerotiorin as lead compound and bioactivity screening under the concentration of 20ppm for various bacteria, such as Pythium dissimile, Alternaria solani, Botryotinia fuckeliana and Gibberella zeae. The results showed that compound 11-10 had better fungicidal acitivity for Phytophthora infestans and Pythium dissimile. Withâ…¡-10 as lead compound, we further modified C-5 site, and compound III-1 was found to have excellent and broad fungicidal activity. With compound III-1 as second lead compound, further acylation of the hydroxyl group for C-7 site has shown no activity at all, which showed that hydroxyl group at C-7 site is benefical for its bioactivity. The substitution of oxygent at C-2 site with nitrogen for compound III-3 has shown little bioactivity drop and the nitrogen atom at C-2 site is unbenefical for its activity. Keeping hydroxyl group at C-7 site, we further modified the C-l and C-5 sites, and compoundsâ…£-1 andâ…£-2 were obtained. However, the introduction of methyl group at C1 site has significantly decreased the bioactivity. The introduction of methyl group at C-5 site in compound IV-1 has further improved its fungicidal acitivity. It was noted that, compoundâ…£-1 could realized 99% suppressing for Uromyces viciae-fabae, Pythium dissimile, Alternaria solani and Gibberella zeae, which showed the value for further studies.4. All these compounds were screened with fungicial activity, and these compounds would lose their fungicidal activity under basic conditions, and have short half-life period under sunshine. The subsequent emphasis would focus on the increasing of their stabilities. Meanwhile, we found the natural product karrikinolide has similar bicyclic skeleton with sclerotiorin, which also has very good stability and bioactivity. Thus, we hope to obtain their derivatives with good fungicidal activity and high stability by introducing the furo[2,3-c]pyran skeleton.5. This thesis firstly summarized the structure and fugicidal acitivty of sclerotiorin derivatives, which offered theorical guide for further design and synthesis of sclerotiorin derivatives with higher bioactivity.
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