柠檬醛基缩氨基硫脲化合物的合成及除草活性

Synthesis and Herbicidal Activity of Citral-based Thiosemicarbazone Compounds

为开发高效除草剂,设计合成了26个新型柠檬醛基缩氨基硫脲化合物2a^2m(13对(2 Z,1 E)/(2 E,1 E)-异构体),采用FT-IR、NMR以及ESI-MS等分析手段对目标化合物的结构进行了表征,并初步测试了相关化合物对油菜(Brassica campestris)和稗草(Echinochloa crusgalli)的除草活性。结果表明:当质量浓度为100 mg/L时,化合物(2 Z,1 E)-2a(R=Me)、(2 E,1 E)-2a(R=Me)、(2 Z,1 E)-2b(R=Et)、(2 E,1 E)-2b(R=Et)和(2 E,1 E)-2c(R=i-Pr)对油菜的胚根生长的抑制活性分别为82.6%、88.7%、80.2%、80.5%和82.0%,远优于商业除草剂丙炔氟草胺的活性。含有脂肪族基团的化合物的除草活性优于具有芳香族基团的化合物,当取代基为脂肪族基团时,(2 E,1 E)-化合物比相应的(2 Z,1 E)异构体活性好,而当取代基为芳香族基团时则相反。计算并分析了最佳活性化合物(2 E,1 E)-2a的静电势和前线分子轨道,说明硫脲部分对生物活性至关重要,而且小的R基团对生物活性有利。

Twenty-six novel citral-based thiosemicarbazone compounds 2a-2m(thirteen pairs of(2 Z,1 E)/(2 E,1 E)-isomers)were designed and synthesized in an attempt to develop potent herbicidal agents.The structures of the target compounds were characterized by FT-IR,NMR,and ESI-MS.The herbicidal activities of the target compounds were preliminarily evaluated in vitro against Brassica campestris and Echinochloa crusgalli.The bioassay results indicated that compounds(2 Z,1 E)-2a(R=Me),(2 E,1 E)-2a(R=Me),(2 Z,1 E)-2b(R=Et),(2 E,1 E)-2b(R=Et),and(2 E,1 E)-2c(R=i-Pr)displayed inhibition rates of 82.6%,88.7%,80.2%,80.5%and 82.0%,respectively,against the root-growth of rape(Brassica campestris)at the concentration of 100 mg/L.They were much better herbicidal activity than the commercial herbicide flumioxazin.It was found that the herbicidal activity of the compounds with aliphatic groups(R)was much better than that of the compounds with aromatic groups(R),and the(2 E,1 E)-isomers bearing aliphatic groups(R)exhibited better inhibition activity than corresponding(2 Z,1 E)-isomers,whereas the(2 Z,1 E)-isomers bearing aromatic groups(R)showed better inhibition activity than their(2 E,1 E)-isomers.The electrostatic potential and the frontier molecular orbitals of the best activity compound(2 E,1 E)-2a were calculated and analyzed.This implied that the thiourea moiety was critical for the bioactive performance and the small R group was favorable for bioactivity.