Synthesis And Fungicidal Activity Of Benzoylureas Containing Benzimidazole

In recent years, more and more plant pathogen resistance to fungicides were reported, challenge to the discovery of new fungicides were urgent. How to create new fungicides with high efficiency, low toxicity, good systematic activity, low resistance has attracted people’s attention. And the emergence of heterocyclic compounds just open up a new path for the synthesis of new pesticides.Heterocyclic compounds, especially the compounds including N atom, were focused on due to the structural diversity, high selectivity, good reactivity, low toxicity and residue. Benzimidazole derivatives are the representative of the heterocyclic compounds including N atom. Carbendazim and Benomyl, including benzimidazole, have been commercialized in the 1960 s, and have been broadly used until now. New fungicides containing benzimidazole are developed constantly, such as Thiophanate-Methyl, which hinted that this kind of compounds always showed good fungicidal activity and were valuable for further development.Chitin is an important component of fungal cell walls, but absent in mammals and plants, therefore any compounds which interfere the synthesis of chitin will affect the biosynthesis of chitin, and show fungicidal activity.In order to discover new fungicides with highly activity and accordance with the IPM, targeted at chitin in fungi, benzimidazoles were introduced to benzoylureas, which is a kind of chitin synthesis inhibitors. Two series of new compounds were designed and synthesized, and the following work were studied.1. Based on the biorational design, 2 series of new compounds were designed by inducing alcohol containing benzimidazole into the BPUs. The general structures are shown below:2. 27 new compounds of BPUs containing benzimidazole were synthesized by 4~5 step’ reaction from the starting materials of substituted benzoic acid, o-phenylenediamine et al, and their structures were confirmed by IR, 1H NMR and EA.3. The synthesis and the methods of post-processing of the key intermediates and the target molecules were discussed, and the 1H-NMR, IR data were analyzed herein.4. The fungicidal activity in vitro against 6 phytopathogens was carried out by mycelium growth rate method at the concentration of 50 mg L-1. The results showed that compounds of seriesⅠexhibited certain fungicidal activity. The inhibitory rates of compound Ib, Ii and Il against Magnaporthe oryzae were 43.14%, 59.48% and 43.14% respectively, which were higher than the control 95% Chlorothalonil(42.16%); the inhibitory rate of compound Im against Botrytis cinerea was 58.88%, which was higher than the control 95% Chlorothalonil(50.66%). Compounds of seriesⅡalso showed certain inhibitory activity against 6 phytopathogens. The inhibitory rate of compound Ⅱg against Magnaporthe oryzae was 47.70%, which was higher than the control 95% Chlorothalonil(42.16%); and the inhibitory rate of compound Ⅱc against Botrytis cinerea was 52.03%, which was higher than the control 95% Chlorothalonil(50.66%).5. The preliminary structure-activity relationship(SAR) of seriesⅠand Ⅱwere studied. About the seriesⅠ, the fungicidal activity of compounds in which R were 2-electron-withdrawing groups were higher than that of 3- or 4- electron-withdrawing groups. But the fungicidal activity of compound when R was 4-Cl was higher than that of 2- or 3-Cl. The fungicidal activity of compounds when R were 3-electron donating groups were higher than that of 2- or 4- electron donating groups. About the seriesⅡ, the fungicidal activity of compounds in which R were electron-donating groups were higher than the electron-withdrawing groups, but it exhibited higher inhibitory activity when R was-Br.