Studies On The Design And Synthesis And Antimicrobial Activities Of New Pyrimidine Derivatives And Benzophenone Derivatives

Agriculture is an important foundation for good and harmonious development of society and economy. But crops are suffering more and more serious diseases under the influence of weather or various anthropic factors. Using agrochemicals is a main method to control plant diseases, protect crops and maintain sustainable agricultural development. The agrochemicals used widely include pesticides, fungicides and herbicides. In recent years, the fungicide market is expanding, and resistance is easily found in the field when a class of agrochemicals has been used for a long time. So looking for new fungicides with different modes of action is of great significance.Encouraged by the lead compounds pyrimethanil and flumorph, we have designed and synthesized two series of compounds. Their biological activities were studied respectively.1. After doing a lot of studies on the development of pyrimidine fungicides such as pyrimethanil, a series of pyrimidine derivatives was designed and synthesized. The starting materials6-hydroxy-2-isopropyl-4-methyl-pyrimidine-or4.6-dimethoxy-2-aminopyrimidine were reacted with several amines, acylhalide or carboxylic acids respectively to give three classes of new primidine derivatives. The antifungal activities of most of the compounds were equal to or higher than those of the commercial fungicides (flumorph and dimethomoiph). Compounds1c.4b and4c showed better activities to GF than the lead compound (pyrimethanil). Compound lc was more potent to AM than pyrimethanil. Compounds lc and3a displayed certain broad-spectrum activities towards the tested fungi. Compounds4a.4b,4c and4d showed relatively moderate antifungal activities. The preliminary SAR can offer great help to design more active compounds as potent fungicides.2. The flumorph and dimethomoiph are two traditional fungicides, which are widely used in the field. Pyrimorph and metrafenone were developed recently as two successful fungicides. The structures of these compounds all contained benzophenone skeleton. According to the basic principles of molecular design, we have synthesized a series of benzophenone derivatives, including12new compounds and4known compounds. And their bioactivities were tested. The bioactivity evaluation indicated that the synthesized compounds were quite potent on most of the tested fungi, but much less effective on the five tested vibrios. At least one of the novel benzophenone derivatives gave higher activity than flumorph and dimethomorph towards the tested fungi. Compounds10a and10b exhibited relatively good activities against five fungi, making them to.be interesting lead compounds for the design and optimization of new fungicides. Six compounds (5c,9a,10c,10e,11b and11e) had effects on all of the tested fungi from different genera and showed good wide-spectrum activities. The screened compound5b might be a better candidate than carbendazim to inhibit Fusarium oxysporum f. spp. Vasinfectum, The preliminary SAR analysis showed that one chloride atom, a benzene ring substituted by three methoxy groups and a pyrimidine group might be favorable for increasing antifungal activities. The SAR discussed preliminarily could be somewhat helpful to design more potent derivatives and to discovery better fungicides with different modes of action.