Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety
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doi: 10.1007/s40242-020-0003-8
Article
Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety ZHAO Yang, CHENG Jingli *, XIE Zhengang, FANG Shaowei and ZHAO Jinhao * Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insert, Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, P. R. China Abstract In order to develop novel spirocyclic tetronic acid lead compounds, a series of new spirocyclic tetronic acid derivatives containing oxime ether moiety was synthesized and bioassayed. The structures of 16 target co mpounds were characterized by 1H NMR spectra, 13C NMR spectra and high-resolution mass spectrometer(HRMS). Preliminary bioassays indicated that most of the title compounds displayed excellent insecticidal activity against Aphis fabae and Nilaparvata lugens at 100 mg/L. In particular, compound 6k showed the similar activity(LC 50= 6.87 mg/L) against A. fabae as the spirotetramat(LC 50=4.56 mg/L) and had better effects(LC 50=1.64 mg/L) against N. lugens in comparison with spirotetramat(LC 50=7.90 mg/L). The study showed that compound 6k exhibited more promising and broad-spectrum insecticide activity and may serve as a new insecticidal agent for sucking pests. Keywords Spirocyclic tetronic acid derivative; Insecticidal activity; Oxime ether moiety
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Introduction
Sucking insect pests can cause tremendous damage in agronomic and horticultural cropping systems[1]. The heavy use of insecticides has led to a gradual increase in pest resistance[2]. Therefore, it is still urgent to develop more efficient and low-risk insecticides for guarantee sustainable control[3]. Spirocyclic tetronic acid derivatives are novel pesticides developed by Bayer CropScience AG. Spirodiclofen, spiromesifen and spirotetramat are three representative commercial varieties[4,5], which have a novel mode of action, and excellent biological activity[6]. In particular, spirotetramat is a fully systemic insecticide and has been extensively employed to fight against a broad range of sucking pest, such as aphids, mealy
bugs, psyllids and whiteflies[7]. Once foliar sprayed and penetrated into the plant, spirotetramat is hydrolyzed at position C-4 to its enol form. As a weak acid, this enol form moves upwards and downwards through its translocation in the xylem and phloem of the plant, respectively. This new two-way systemicity ensures the control of hidden pests, such as root aphids and the protection of new shoots or leaves appearing[2]. Unfortunately, the enol form is prone to be inactivated by demethylation at position C-8[8]. Therefore, it is necessary to modify position C-8 to improve its metabolic stability[9](Fig.1). Oxime ether group is an active group and exists in many biological molecules[10—12]. Recently, Palani et al.[13] higlighted that the oxime linker can result in great metabolic
Fig.1 Design of title compounds 6a—6m and 7a—7c ——————————— *Corresponding authors. Email: [email protected]; [email protected]
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