A dynamic NMR study of the nitrogen lone pair orientation in 2-benzoyl-5-methyl-5-aza-1,3-dithiacyclohexane

1989 ◽  
Vol 67 (12) ◽  
pp. 2067-2070 ◽  
Author(s):  
B. Mario Pinto ◽  
Blair D. Johnston ◽  
Ruby Nagelkerke ◽  
Eusebio Juaristi ◽  
Eduardo A. González
Keyword(s):  
Magnetization Transfer ◽  
Lone Pair ◽  
Anomeric Effect ◽  
Saturation Transfer ◽  
Nuclear Overhauser Enhancement ◽  
Free Energy Of Activation ◽  
Nmr Study ◽  
Nitrogen Lone Pair ◽  
Nuclear Overhauser ◽  
Related Compounds

Nuclear Overhauser enhancement difference experiments and magnetization transfer experiments on 2-benzoyl-5-methyl-5-aza-1,3-dithiacyclohexane 1 at 186 K show conclusively that the N-methyl group adopts a preferred axial orientation. The result has implications for evaluation of the origin of the anomeric effect in this and related compounds. The free energy of activation for ring interconversion in 1 is estimated by spin saturation transfer experiments to be 10.7 ± 0.4 kcal mol−1. Keywords: D NMR, conformational analysis, nuclear Overhauser enhancement, saturation transfer.

Orientation of the methoxyl group in cis- and trans-2-methoxy-4-methyl-1,3-dioxanes and related compounds as inferred by 1H and 13C nmr spectroscopy. The significance of the "exo-anomeric" effect

1982 ◽  
Vol 60 (9) ◽  
pp. 1067-1072 ◽  
Author(s):  
Vanga S. Rao
Keyword(s):  
Dynamic Equilibrium ◽  
Chemical Shifts ◽  
13C Nmr Spectroscopy ◽  
Methoxyl Group ◽  
Anomeric Effect ◽  
1H And 13C Nmr ◽  
Nuclear Overhauser ◽  
Cis And Trans ◽  
In Cis ◽  
Related Compounds

Carbon-13 chemical shifts and 13C—1H couplings are reported for some substituted 2-methoxy-1,3-dioxanes and related tetrahydropyran derivatives. These data, together with nuclear Overhauser enhancement experiments, provided evidence for a favored orientation of the methoxyl group. From an analysis of the 13C chemical shifts and the magnitude of vicinal 13C—1H coupling between —OCH3 and H-2, a possible dynamic-equilibrium orientation for the methoxyl group is proposed, and an evaluation of the significance of a "generalized exo-anomeric effect" is presented.

scholarly journals Nuclear Overhauser Enhancement Mediated Chemical Exchange Saturation Transfer Imaging at 7 Tesla in Glioblastoma Patients

PLoS ONE ◽  
2014 ◽  
Vol 9 (8) ◽  
pp. e104181 ◽  
Author(s):  
Daniel Paech ◽  
Moritz Zaiss ◽  
Jan-Eric Meissner ◽  
Johannes Windschuh ◽  
Benedikt Wiestler ◽  
...  
Keyword(s):  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
7 Tesla ◽  
Saturation Transfer ◽  
Nuclear Overhauser Enhancement ◽  
Nuclear Overhauser

scholarly journals NMR studies on carbohydrate interactions with DC-SIGN towards a quantitative STD analysis

2013 ◽  
Vol 85 (9) ◽  
pp. 1771-1787 ◽  
Author(s):  
Cinzia Guzzi ◽  
Juan Carlos Muñoz-García ◽  
Pedro M. Enriquez-Navas ◽  
Javier Rojo ◽  
Jesús Angulo ◽  
...  
Keyword(s):  
Dendritic Cell ◽  
Saturation Transfer ◽  
Nmr Studies ◽  
Saturation Time ◽  
Nuclear Overhauser Enhancement ◽  
Saturation Transfer Difference ◽  
Std Nmr ◽  
Simple Carbohydrates ◽  
Nuclear Overhauser ◽  
Terminal Mannose

The recent introduction of saturation transfer difference (STD) NMR has increased the tools for the study of protein–carbohydrate complexes. This is useful when it is combined with transfer nuclear Overhauser enhancement spectroscopy (NOESY) measurement, or when it is interpreted using the expected calculated values of transference, yielding additional, very valuable information for the study of this type of complex. The objective of this work is to cover the advances of the STD technique as exemplified by the investigations of DC-SIGN (dendritic cell-specific ICAM-3 grabbing non-integrin) recognition by simple carbohydrates or mimics of them, based on structures containing a terminal mannose or fucose. We also will discuss the methods for quantification of the STD values based on the initial growing rates with the saturation time.

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