title: Synthesis, crystal structure, herbicidal activities and 3D-QSAR study of some novel 1,2,4-triazolo[4,3-a]pyridine derivatives.
abstract: BACKGROUND
  1,2,4-Triazolo[4,3-a]pyridine derivatives represent a new series of compounds that possess good herbicidal activity against Echinochloa crusgalli (L.) Beauv., Setaria faberii, Digitaria sanguinalis (L.) Scop., Brassica juncea Coss., Amaranthus retroflexus L. and Eclipta prostrata L.
  
  
  RESULTS
  A total of 23 novel 1,2,4-triazolo[4,3-a]pyridine derivatives were synthesised and identified by (1) H NMR, IR, single-crystal X-ray diffraction, mass-spectroscopic and elemental analysis, and their herbicidal activities were tested against E. crusgalli (L.) Beauv., S. faberii, D. sanguinalis (L.) Scop., B. juncea Coss., A. retroflexus L. and E. prostrata L. at 150 g a.i. ha(-1) . It was found that the title compound 8-chloro-3-(4-propylphenyl)-[1,2,4]-triazolo[4,3-a]pyridine possesses high herbicidal activity and a broad spectrum against the 22 test weeds, with an inhibition effect of about 50% at a dosage of 37.5 g a.i. ha(-1) , and is safe for corn, cotton and rice at a dosage of 150 g a.i. ha(-1) . Furthermore, comparative molecular field analysis contour models were established to study the structure-activity relationship of the title compounds.
  
  
  CONCLUSIONS
  It is possible that, with further structure modification, 1,2,4-triazolo[4,3-a]pyridine derivatives, which possess good herbicidal activities, may become novel lead compounds for the development of herbicides against dicotyledonous weeds.
authors.affiliation: College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou, China.
authors.forename: Xing-Hai
authors.initials: XH
authors.lastname: Liu
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Xu
authors.forename: Cheng-Xia
authors.initials: CX
authors.lastname: Tan
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Weng
authors.forename: Jia-Hua
authors.initials: JH
authors.lastname: Xin
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
mesh_terms: D006540:Herbicides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D019684:Magnoliopsida / Q000187:drug effects*; D057685:Plant Weeds / Q000187:drug effects*; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D021281:Quantitative Structure-Activity Relationship; D013045:Species Specificity; D014230:Triazoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D006540:Herbicides; D011725:Pyridines; D014230:Triazoles
keywords: 1,2,4-triazolo[4,3-a]pyridine; 3D-QSAR; crystal structure; herbicidal activities; synthesis