title: Synthesis and fungicidal activity of pyrazole derivatives containing 1,2,3,4-tetrahydroquinoline.
abstract: BACKGROUND
  Take-all of wheat, caused by the soil-borne fungus Gaeumannomyces graminis var. tritici, is one of the most important and widespread root diseases. Given that take-all is still hard to control, it is necessary to develop new effective agrochemicals. Pyrazole derivatives have been often reported for their favorable bioactivities. In order to discover compounds with high fungicidal activity and simple structures, 1,2,3,4-tetrahydroquinoline, a biologically active group of natural products, was introduced to pyrazole structure. A series of pyrazole derivatives containing 1,2,3,4-tetrahydroquinoline were synthesized, and their fungicidal activities were evaluated.
  
  
  RESULTS
  The bioassay results demonstrated that the title compounds displayed obvious fungicidal activities at a concentration of 50 μg/mL, especially against V. mali, S. sclerotiorum and G. graminis var. tritici. The inhibition rates of compounds 10d, 10e, 10h, 10i and 10j against G. graminis var. tritici were all above 90 %. Even at a lower concentration of 16.7 μg/mL, compounds 10d and 10e exhibited satisfied activities of 100 % and 94.0 %, respectively. It is comparable to that of the positive control pyraclostrobin with 100 % inhibition rate.
  
  
  CONCLUSIONS
  A series of pyrazole derivatives containing 1,2,3,4-tetrahydroquinoline were synthesized and their structures were confirmed by (1)H NMR, (13)C NMR, IR spectrum and HRMS or elemental analysis. The crystal structure of compound 10g was confirmed by X-ray diffraction. Bioassay results indicated that all title compounds exhibited obvious fungicidal activities. In particular, compounds 10d and 10e showed comparable activities against G. graminis var. tritici with the commercial fungicide pyraclostrobin at the concentration of 16.7 μg/mL.Graphical abstractA series of pyrazole derivatives containing 1,2,3,4-tetrahydroquinoline were designed and synthesized. Bioassay results indicated that all these compounds exhibited obvious fungicidal activities.
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Peng
authors.initials: P
authors.lastname: Lei
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Xuebo
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Gaofei
authors.initials: G
authors.lastname: Xu
authors.affiliation: Department of Plant Pathology, China Agricultural University, Beijing, 100193 China.
authors.forename: Xili
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Xinling
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Xiaohe
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193 China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ling
keywords: 1,2,3,4-tetrahydroquinoline; Fungicidal activity; Pyrazole; Synthesis; Wheat take-all