Design, Synthesis And Activity Study Of New Herbicide Safeners For The Damage From S-Metolachlor

S-metolachlor is a kind of amide herbicide,which is mainly used to control some small-seed broad-leaved weeds and annual grasses with large dosage in field and obvious phytotoxicity.Femclorim is a pyrimidine safener with large dosage and simple chemical structure,which is easy to be modified.However,its structure contains chlorine atoms that are slightly toxic to mammals,so it has potential harm to environment.Sanshools,a natural product has safener activity,which is not only of great research value in the field of drug development,but also friendly to environment.Therefore,based on the status and S-metolachlor phytotoxicity,it is urgent to develop new herbicide safener that is environmental-friendly and effective by modifying the structures of femclorim and sanshool compound.Since the structure of commercial oxime ether herbicide safeners contain ether linkage,the series Ⅰ compounds and 4-chloro-6-(substituted phenoxy)-2-phenylpyrimidine compounds are designed by replacing the chlorine atom of femclorim with ether linkage.Then,the active substructure splicing is adopted to design the series Ⅱ compounds and(E)-4-(2-benzilidene hydraiino)-6-chlorine-2-phenylpyrimidine compounds by replacing the chlorine atoms of femclorim with active fragments(-C=NNH-)that can regulate plant growth.According to chemical structural formulas of natural product of sanshools,the series Ⅲ compounds are designed and the amide compounds are replaced with N-alkyl and N-alkenyl.There is a total of 86 compounds.When safety activity test,herbicide safener test,or bacteriostatic activity test are carried out on series Ⅰ,Ⅱ and Ⅲ compounds,the results show that Ⅰ and Ⅱ at the concentrations of 1mg/L,as well as Ⅲ at the concentration of 8 mg/L have almost no inhibitory effect on rice growth,and 90.70% of compounds in series Ⅰ,Ⅱ and Ⅲ have detoxification effects against S-metolachlor phytotoxicity to rice,which have safener activity.Taking femclorim as the positive control and plant height of rice as the criterion,Ⅰ-05,Ⅰ-08,Ⅱ-09,Ⅱ-20,Ⅲ-06 and Ⅲ-28 are selected as compounds with high activity.When the concentration reduction test is carried out on these 6 compounds,the following conclusions can be drawn: the detoxification of Ⅰ-05,Ⅱ-09,Ⅱ-20,Ⅲ-06 and Ⅲ-28 to S-metolachlor reaches the peak at the concentration of 0.05 mg/L,0.5 mg/L,0.025 mg/L,0.25 mg/L and 1 mg/L.The detoxification ability of Ⅰ-05 and Ⅱ-09 was much better than that of herbicide at the optimum concentration.The detoxification ability of the other four compounds(Ⅱ-20,Ⅲ-06 and Ⅲ-28)was close to that of herbicide at the optimum concentration.The detoxification of Ⅰ-08 to S-metolachlor is similar to that of femclorim at the concentrations of 0.025 mg/L,0.05 mg/L and 0.1 mg/L,but the optimum concentration can not be determined.The above 6 compounds have the advantages of simple structure,easy synthesis and environmental friendliness,so they can be used in new green herbicide safener.At the concentration of 50 mg/L,the target compounds of series Ⅰ and Ⅱ show certain inhibitory effects on such 4 pathogenic bacteria as Sclerotinia sclerotiorum,Fusarium graminearum,Fusarium oxysporum and Thanatephorus cucumeris with active antifungal structure.