Synthesis And Fungicidal Activity Of Hexahydro-2H-benzo[e][1,2,4]thiadiazin-3(4H)-one1,1-dioxide

Sclerotinia sclerotiorum of rape and Botrytis cinerea of tomato will seriously endanger the yield of vegetables,fruits and other crops.At present,chemical pesticides are the main means to control Sclerotinia sclerotiorum of rape and Botrytis cinerea of tomato,but the problem of drug resistance has become more and more serious in recent years.In this experiment,taking Sclerotinia sclerotiorum and Botrytis cinerea as the main control targets,30 hexahydro-2H-benzo[e][1,2,4]thiadiazin-3（4H）-one 1,1-dioxide compounds were synthesized.Alkyl,phenyl,benzyl and phenylethyl were connected to the skeleton of thiadiazine.The structure of compounds were confirmed by ¹H NMR,¹³C NMR and HRMS.The structure of compound WY-24 was confirmed by X-ray single crystal diffraction（CCDC:2156433）.In the process of determining the structure,the spatial isomerism of this series of compounds was determined by liquid chromatography and high-resolution mass spectrometry.All the 30 target compounds in this series passed the structural detection.In vitro fungicidal activity test was carried out on 30 target compounds.According to the fungicidal activity test results,it can be seen that the target compounds are effective against Rhizoctonia solani KüHN,Fusarium graminearum,Botrytis cinerea,Sclerotinia sclerotiorum and Pyricularia grisea.There was no significant inhibition effect on bacteria such as Erwinia carotovora,Xanthomonas campestris pv.Citri Hasse dye,Xanthomonas oryzae Dowson,Bacillus subtilis,Escherichia coli and Pseudomonas aeruginosa.For Botrytis cinerea,the inhibition rate of WY-13,WY-14 and WY-20 was more than 70%,and the highest was WY-14,which was close to 82.61%of pyridylamide.The inhibition rate data of most target compounds on Sclerotinia sclerotiorum were very ideal.the highest inhibition rate was WY-22.Overall,the inhibition rates of WY-17 on five fungus exceeded 50%,showing a good broad spectrum.Secondly,WY-14 also showed a good broad spectrum,with an inhibition rate of more than 50%on four fungus.The compounds with good inhibition effect on Sclerotinia sclerotiorum were re screened.According to the re screening results,among the 21 re screened compounds,the EC₅₀of20 compounds is less than 10μg·m L^-1,in which the EC₅₀of WY-13,WY-17,WY-22 and WY-25 is less than 1μg·m L^-1,WY-22 is the minimum,which is 0.0638μg·m L^-1.It can be seen from these data that this series of compounds have good inhibitory effect on Sclerotinia sclerotiorum of rape.This series of compounds have carried out in vivo pot experiments with Sclerotinia sclerotiorum of rape,Botrytis cinerea of tomato and Blumeria graminis f.sp.tritici of wheat as targets.There are 10 compounds with good control effect on Sclerotinia sclerotiorum of rape and 13 compounds with good control effect on Botrytis cinerea of tomato.Among them,WY-22 has the best inhibition rate on Sclerotinia sclerotiorum with inhibition rates of82.95%.There are 10 compounds with good effect on Blumeria graminis f.sp.tritici.Among the standard compounds,the inhibition rate of WY-13 on Blumeria graminis f.sp.tritici was94.5%,the same as that of WY-22.For Botrytis cinerea,the compound with the best control effect was WY-10,and the inhibition rate reached 88.08%.The R group at position 2 about hexahydro-2H-benzo[e][1,2,4]thiadiazin-3（4H）-one1,1-dioxide.In terms of structure-activity relationship,the activity was the best when R group was substituted phenyl,in which the activity of monosubstituted phenyl was better than that of disubstituted phenyl,and finally trisubstituted phenyl.When R was monosubstituted benzene When the substituent is at position 4,the activity of the compound substituted by halogen atom is greater than that of nitro substituent and trifluoromethyl substituent,and finally methoxy substituent.Among them,when the substituent is at position 4,the activity of the compound is the best.