Exploration of Novel Botanical Insecticide Leads: Synthesis and Insecticidal Activity of β‑Dihydroagarofuran Derivatives

The
discovery of novel leads and new mechanisms of action is of
vital significance to the development of pesticides. To explore lead
compounds for botanical insecticides, 77 β-dihydroagarofuran
derivatives were designed and synthesized. Their structures were mainly
confirmed by 1H NMR, 13C NMR, DEPT-135°,
IR, MS, and HRMS. Their insecticidal activity was evaluated against
the third-instar larvae of Mythimna separata Walker, and the results indicated that, of these derivatives, eight
exhibited more promising insecticidal activity than the positive control,
celangulin-V. Particularly, compounds 5.7, 6.6, and 6.7 showed LD50 values of 37.9, 85.1,
and 21.1 μg/g, respectively, which were much lower than that
of celangulin-V (327.6 μg/g). These results illustrated that
β-dihydroagarofuran ketal derivatives can be promising lead
compounds for developing novel mechanism-based and highly effective
botanical insecticides. Moreover, some newly discovered structure–activity
relationships are discussed, which may provide some important guidance
for insecticide development.