Synthesis And Fungicidal Activity Of Benzoylureas Containing Pyridoxine

With the increasing awareness of environmental protection,the corresponding pest control concepts have also undergone great changes,from the traditional maximum "killing"to scientific and reasonable "control".People pay more attention to the safety to human beings,environment and non-target organisms rather than the high biological activity.Chitin is an indispensable component of fungi and insects,and absent in plants and mammals.Therefore,chitin synthesis inhibitors have attracted people’s attention.Benzoylureas are typical chitin synthesis inhibitors,but resistance have occurred inevitably during long-term use,and the development of new compounds is urgent.Development of pesticide has entered an era of heterocycles.Pyridoxine contains O and N atoms,which are easy to form hydrogen bonds in organisms.The introduction of pyridoxine into benzoylureas is expected to obtain new fungicides with good biocompatibility.In this paper,pyridoxine is introduced into benzoyl urea through active substructure splicing and biological isosteric substitution,and benzoylureas containing pyridoxine are designed and synthesized.The fungicidal activity has been tested and preliminary structure-activity relationship was studied.The following work were carried out:1.13 compounds of benzoylureas containing pyridoxine were synthesized through 7-step reactions such as chlorination,ammonolysis with benzoic acid and pyridoxine as the starting materials.The general structure is as follows.R:-R;OR;-X-NO₂Ia～Im2.Structure of the target compounds were confirmed by ¹H NMR,¹³C NMR,IR and MS,and the spectrum were analyzed herein.3.The fungicidal activities in vitro against Rhizoctorzia solani,Eggplant Sclerotiorum,Magnaporthe oryzae and Gibberella zeae were carried out by mycelial growth rate method at the concentration of 50 μg/mL.The results showed that all the target compounds exhibited excellent inhibitory activity against Eggplant Sclerotiorum,and the inhibitory rate was generally higher than 60.00%.Among them,the inhibition rates of compounds Ic,Ig and Ih were 78.25%,81.43%,78.33%,which were equivalent to the control,and the EC50 values of Ih and Ii were 1.46 μg/mL and 1.31 μg/mL respectively;Compounds Ic,Ii and Ik showed certain fungicidal activities against Rhizoctorzia solani,with inhibition rates 43.79%,42.97%,and 42.15%;Compound Ih showed certain inhibitory effect on Gibberella zeae,with an inhibition rate of 46.02%;Compound Ii has a good inhibitory effect on Magnaporthe oryzae.4.The preliminary structure-activity relationship were discussed.Totally,the fungicidal activities of compounds with electron-donating groups were higher than that of electron-withdrawing groups.The 4-position substitution compounds exhibited better inhibitory effect towards Eggplant Sclerotiorum.Most of the 4-position substitution compounds showed better fungicidal activity against Rhizoctorzia solani than the 2-and 3-position substitutions,and most of the 3-and 4-substituted compounds exhibitied better activities against Gibberella zeae.The target compounds synthesized exhibited certain fungicidal activities,and some of the compounds showed remarkable fungicidal activities,which is of further research significance.The results provided experimental data and theoretical basis for the development of benzoylureas.