Spirodiclofen ether derivatives: semisynthesis, structural elucidation, and pesticidal activities against Tetranychus cinnabarinus Boisduval , Aphis citricola Van der Goot and Mythimna separata Walker

2021 ◽  
Author(s):  
Shaochen Li ◽  
Min Lv ◽  
Tianze Li ◽  
Meng Hao ◽  
Hui Xu
Keyword(s):  
Structural Elucidation ◽  
Tetranychus Cinnabarinus ◽  
Mythimna Separata ◽  
Aphis Citricola

Isolation and structural elucidation of novel natural compounds from twigs of Pinus banksiana

Planta Medica ◽  
2013 ◽  
Vol 79 (13) ◽  
Author(s):  
C Si ◽  
X Ren ◽  
S Liu ◽  
G Xu ◽  
J Jiang
Keyword(s):  
Pinus Banksiana ◽  
Natural Compounds ◽  
Structural Elucidation

Detection, Identification and Structural Elucidation of Flavonoids using Liquid Chromatography Coupled to Mass Spectrometry

2020 ◽  
Vol 24 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Krzysztof Kamil Wojtanowski ◽  
Tomasz Mroczek
Keyword(s):  
Mass Spectrometry ◽  
Central Nervous System ◽  
Nuclear Magnetic Resonance ◽  
Liquid Chromatography ◽  
High Performance ◽  
Short Review ◽  
Structural Elucidation ◽  
High Throughput Analysis ◽  
Protective Actions ◽  
The Central Nervous System

Flavonoids are one of the most common secondary metabolites occurring in plants. Their activity in the Central Nervous System (CNS) including sedative, anxiolytic, anti-convulsive, anti-depressant and neuro-protective actions is well known and documented. The most popular methods for detection, identification and structural elucidation of flavonoids are these based on Nuclear Magnetic Resonance (NMR) and mass spectrometry (MS). NMR allows rapid, high throughput analysis of crude extracts and also gives stereochemical details about identified substances. However, these methods are expensive and less sensitive than MS-based techniques. Combining High Performance Liquid Chromatography (HPLC) with MS detection gives the most powerful tool for analysis of flavonoids occurring in plants. There is a lot of different approaches to use LC/MS based techniques for identification of flavonoids and this short review shows the most important.

Combinatorial Synthesis of Novel 9R-Acyloxyquinine Derivatives as Insecticidal Agents

2020 ◽  
Vol 23 (2) ◽  
pp. 111-118
Author(s):  
Zhiping Che ◽  
Jinming Yang ◽  
Di Sun ◽  
Yuee Tian ◽  
Shengming Liu ◽  
...  
Keyword(s):  
Natural Products ◽  
Double Bond ◽  
Insecticidal Activity ◽  
Structural Modification ◽  
Combinatorial Synthesis ◽  
Hydroxyl Group ◽  
Botanical Insecticide ◽  
Mythimna Separata ◽  
Lead Compounds

Background: It is one of the effective ways for pesticide innovation to develop new insecticides from natural products as lead compounds. Quinine, the main alkaloid in the bark of cinchona tree as well as in plants in the same genus, is recognized as a safe and potent botanical insecticide to many insects. The structural modification of quinine into 9R-acyloxyquinine derivatives is a potential approach for the development of novel insecticides, which showed more toxicity than quinine. However, there are no reports on the insecticidal activity of 9Racyloxyquinine derivatives to control Mythimna separata. Methods: Endeavor to discover biorational natural products-based insecticides, 20 novel 9Racyloxyquinine derivatives were prepared and assessed for their insecticidal activity against M. separata in vivo by the leaf-dipping method at 1 mg/mL. Results: Among all the compounds, especially derivatives 5i, 5k and 5t exhibited the best insecticidal activity with final mortality rates of 50.0%, 57.1%, and 53.6%, respectively. Conclusion: Overall, a free 9-hydroxyl group is not a prerequisite for insecticidal activity and C9- substitution is well tolerated; modification of out-ring double-bond is acceptable, and hydrogenation of double-bond enhances insecticidal activity; Quinine ring is essential and open of it is not acceptable. These preliminary results will pave the way for further modification of quinine in the development of potential new insecticides.

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

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