Stereoselective synthesis of 4β-acyloxypodophyllotoxin derivatives as insecticidal agents

As our ongoing work on research of natural-product-based insecticidal agents, some 4α/β-acyloxypodophyllotoxin derivatives were synthesized, and were evaluated against the pre-third-instar larvae of B. mori, A. dissimilis and M. separate in vivo at the concentration of 1 mg ml^-1, respectively. Among all derivatives, compounds 2 g, h and 4c, d showed more promising insecticidal activities than their precursors - podophyllotoxin and epipodophyllotoxin. Furthermore, derivatives 2 g, h and 4c, d exhibited more relative amicable activities than their precursors - podophyllotoxin and epipodophyllotoxin. This results indicated that 4β-acyloxy moiety in the podophyllotoxin derivatives was significant for obtaining the more potent compounds.