Determination of the Relative Configuration by Distance Geometry Calculations with Proton–Proton Distances from NOESY Spectra

1994 ◽  
Vol 33 (7) ◽  
pp. 753-755 ◽  
Author(s):  
Michael Reggelin ◽  
Matthias Köck ◽  
Kilian Conde-Frieboes ◽  
Dale Mierke
Keyword(s):  
Distance Geometry ◽  
Proton Proton ◽  
Relative Configuration ◽  
Noesy Spectra

scholarly journals Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nilamoni Nath ◽  
Juan Carlos Fuentes-Monteverde ◽  
Dawrin Pech-Puch ◽  
Jaime Rodríguez ◽  
Carlos Jiménez ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Residual Dipolar Couplings ◽  
Chemical Shift Anisotropy ◽  
Dipolar Couplings ◽  
Structural Determination ◽  
Proton Proton ◽  
Relative Configuration ◽  
Similar Information ◽  
3D Molecular Structure

Abstract 3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond 1H,13C residual dipolar couplings (RDCs) or by 13C residual chemical shift anisotropies (RCSAs) provide the relative configuration. However, these RDCs or carbon RCSAs rely on 1% natural abundance of 13C preventing their use for compounds available only in quantities of a few 10’s of µgs. By contrast, 1H RCSAs provide similar information on spatial orientation of structural moieties within a molecule, while using the abundant 1H spin. Herein, 1H RCSAs are accurately measured using constrained aligning gels or liquid crystals and applied to the 3D structural determination of molecules with varying complexities. Even more, deuterated alignment media allow the elucidation of the relative configuration of around 35 µg of a briarane compound isolated from Briareum asbestinum.

scholarly journals The Advanced Floating Chirality Distance Geometry Approach―How Anisotropic NMR Parameters Can Support the Determination of the Relative Configuration of Natural Products

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 330
Author(s):  
Matthias Köck ◽  
Michael Reggelin ◽  
Stefan Immel
Keyword(s):  
Natural Products ◽  
Residual Dipolar Couplings ◽  
Organic Molecules ◽  
Structural Information ◽  
Distance Geometry ◽  
Relative Configuration ◽  
Small Organic Molecules ◽  
Configurational Analysis ◽  
Interproton Distances

The configurational analysis of complex natural products by NMR spectroscopy is still a challenging task. The assignment of the relative configuration is usually carried out by analysis of interproton distances from NOESY or ROESY spectra (qualitative or quantitative) and scalar (J) couplings. About 15 years ago, residual dipolar couplings (RDCs) were introduced as a tool for the configurational determination of small organic molecules. In contrast to NOEs/ROEs which are local parameters (distances up to 400 pm can be detected for small organic molecules), RDCs are global parameters which allow to obtain structural information also from long-range relationships. RDCs have the disadvantage that the sample needs a setup in an alignment medium in order to obtain the required anisotropic environment. Here, we will discuss the configurational analysis of five complex natural products: axinellamine A (1), tetrabromostyloguanidine (2), 3,7-epi-massadine chloride (3), tubocurarine (4), and vincristine (5). Compounds 1–3 are marine natural products whereas 4 and 5 are from terrestrial sources. The chosen examples will carefully work out the limitations of NOEs/ROEs in the configurational analysis of natural products and will also provide an outlook on the information obtained from RDCs.

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

scholarly journals Measuring the quartic Higgs self-coupling at a multi-TeV muon collider

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
M. Chiesa ◽  
F. Maltoni ◽  
L. Mantani ◽  
B. Mele ◽  
F. Piccinini ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Center Of Mass ◽  
Mass Energy ◽  
Simple Analysis ◽  
Proton Proton ◽  
Coupling Interaction ◽  
Center Of Mass Energy ◽  
Muon Collider ◽  
Better Than

Abstract Measuring the shape of the Higgs boson potential is of paramount importance, and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range and luminosities of the order of 1035cm−2s−1, as presently under discussion, might provide, thanks to a rather large three Higgs-boson production and to a limited background. By performing a first and simple analysis, we find a clear indication that a muon collider could provide a determination of the quartic Higgs self-coupling that is significantly better than what is currently considered attainable at other future colliders.

Determination of Relative Configuration in Organic Compounds by NMR Spectroscopy and Computational Methods

ChemInform ◽  
2007 ◽  
Vol 38 (50) ◽  
Author(s):  
Giuseppe Bifulco ◽  
Paolo Dambruoso ◽  
Luigi Gomez-Paloma ◽  
Raffaele Riccio
Keyword(s):  
Nmr Spectroscopy ◽  
Organic Compounds ◽  
Computational Methods ◽  
Relative Configuration
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