Structural Modification of Turpentine with Natural Chiral Preservation and Low-Risk Application Prospects in Crop Protection

For the purpose of chiral pesticide development, the natural chiral structure of turpentine should be applied rationally. Two series of amide derivatives were prepared to study the effect of chiral center retention on the fungicidal activity. The investigation of fungicidal activity against three pathogenic microbes was carried out extensively. Some satisfactory conclusions were obtained from the activity evaluation. Above all, compounds (5′a-l) derived from cis-myrtlecanic acid (a chiral compound obtained from β-pinene) exhibited better activity than compounds (5a-l) derived from dehydrocumic acid (achiral compound obtained from β-pinene). The overall effect was good, and it was remarkable that compounds 5′d (substitute with N-(4-(trifluoromethyl)phenyl), 5′e (substitute with N-(4-fluorophenyl)), and 5′f (substitute with N-(4-chlorophenyl)) demonstrated extremely excellent activity, with EC50 values of 1.604, 1.822, and 2.296 μg/mL against Valsa mali.