Dis-assembling lithium amide ladder structures: structural elucidation of the lithium anilide solvate [{PhN(H)Li}6·8THF], a model intermediate En route to forming tetra-solvated ring dimers

1995 ◽  
pp. 2011-2012 ◽  
Author(s):  
William Clegg ◽  
Lynne Horsburgh ◽  
Fiona M. Mackenzie ◽  
Robert E. Mulvey
Keyword(s):  
Structural Elucidation ◽  
Lithium Amide

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.

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

Isolation and structural elucidation of secondary metabolites obtained from the soft coral Sinularia candidula present in the Egyptian Red Sea

Planta Medica ◽  
2015 ◽  
Vol 81 (16) ◽  
Author(s):  
RF Abou El Ezz ◽  
M Afifi ◽  
A Kamal ◽  
E Sannad ◽  
M Radwan ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Red Sea ◽  
Soft Coral ◽  
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.

Structural elucidation of rhamnogalacturonans from flaxseed hulls

2012 ◽  
Vol 362 ◽  
pp. 47-55 ◽  
Author(s):  
Ke-Ying Qian ◽  
Steve W. Cui ◽  
John Nikiforuk ◽  
H.Douglas Goff
Keyword(s):  
Structural Elucidation

The structural elucidation of the Salmonella enterica subsp. enterica, reveals that it contains both O-factors 4 and 5 on the LPS antigen

2013 ◽  
Vol 370 ◽  
pp. 9-12 ◽  
Author(s):  
Cristina De Castro ◽  
Rosa Lanzetta ◽  
Serena Leone ◽  
Michelangelo Parrilli ◽  
Antonio Molinaro
Keyword(s):  
Salmonella Enterica ◽  
Structural Elucidation
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