Synthesis and insecticidal activity of some novel fraxinellone-based esters.
In continuation of a program aimed at the discovery and development of natural products-based insecticidal agents, two series of novel fraxinellone-based esters were synthesized by modification at the C-4 or C-10 position of fraxinellone and evaluated for their insecticidal activity against the pre-third-instar larvae of  Mythimna separata  in vivo. An efficient method for the stereoselective synthesis of 4α-hydroxyfraxinellone from fraxinellonone was developed, and the steric configuration of 6h was unambiguously confirmed by X-ray crystallography. Among 37 compounds, some derivatives displayed potent insecticidal activity; especially compounds 6h, 6q, 6t, and 7q showed more promising insecticidal activity than toosendanin, a commercial botanical insecticide derived from  Melia azedarach . This suggested that introduction of the fluorine atom on the phenyl ring could lead to a more potent compound than one possessing chlorine or bromine. Meanwhile, introduction of the heterocyclic fragments at the C-4 or C-10 position of fraxinellone was essential for their insecticidal activity. This will pave the way for further design, structural modification, and development of fraxinellone as an insecticidal agent.
Laboratory of Pharmaceutical Design and Synthesis, College of Sciences, Northwest A&F University, Yangling 712100, Shannxi Province, People's Republic of China.
Yong
Y
Guo
Yuanyuan
Y
Yan
Xiang
X
Yu
Yi
Y
Wang
Xiao-Yan
XY
Zhi
Ying
Y
Hu
Hui
H
Xu
D000818:Animals; D001572:Benzofurans / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004952:Esters / Q000737:chemistry*; D007306:Insecticides / Q000138:chemical synthesis*; D007814:Larva; D009036:Moths
D001572:Benzofurans; D004952:Esters; D007306:Insecticides; C075391:fraxinellone