Conformational Study of N-Methyl-5,6-dihydro-7H,12H-dibenz[c,f]-azocine by Nuclear Magnetic Resonance Spectroscopy

1973 ◽  
Vol 51 (20) ◽  
pp. 3380-3385 ◽  
Author(s):  
Roger N. Renaud ◽  
Robert B. Layton ◽  
Robert R. Fraser
Keyword(s):  
Experimental Data ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Conformational Study ◽  
Conjugate Acid ◽  
Trifluoracetic Acid ◽  
Deuterated Derivative ◽  
Conformational Properties ◽  
Crown Form

A study of the n.m.r. spectra of N-methyl-5,6-dihydro-7H,12H-dibenz[c,f]azocine, its deuterated derivative, and its conjugate acid in deuteriochloroform and in trifluoracetic acid at 27 and at −62° has shown that the molecule prefers the rigid "crown" conformation. From the equilibrium constant for the equilibrium flexible [Formula: see text] crown at 27 and at −62°, ΔH and ΔS values of −3.2 ± 0.5 kcal/mol and −7 ± 3 e.u. respectively were determined, indicating the preference for the crown conformer. A barrier to interconversion of the flexible to crown form at −62° was determined to be 15.3 ± 0.3 kcal/mol.These parameters provide the first experimental data pertinent to the conformational properties of the 1,4-cyclooctadiene system.

Conformational Study of N-Alkyl 5,6-Dihydro-7h,12h-Dibenz[C,F]Azocines by Nuclear Magnetic Resonance Spectroscopy

1975 ◽  
Vol 53 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Robert R. Fraser ◽  
Mohammad A. Raza ◽  
Roger N. Renaud ◽  
Robert B. Layton
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Boat Conformation ◽  
Conformational Study ◽  
Conformational Properties ◽  
Boat Form ◽  
Twist Boat ◽  
Influence Of Substituents

The influence of substituents on the conformational properties of N-substituted 5,6-dihydro-7H,12H-dibenz[c,f]azocines and their conjugate acids was studied by n.m.r. spectroscopy. The position of the equilibrium between a rigid boat-chair and a flexible twist-boat conformation has been measured. The twist-boat conformation in deuterochloroform increased as the size of the substituent increased. However, the effect was opposite for the series of conjugate acids in trifluoroacetic acid.A number of inversion barriers for the [Formula: see text] and the [Formula: see text] equilibria in CDCl3 and TFA were determined. It was found that all barriers to interconversion were raised on protonation. The barrier to racemization for the twist-boat form of the quaternary methiodide of 1 was found to be >18 kcal/mol.

Guidelines for the representation of pulse sequences for solution-state nuclear magnetic resonance spectrometry (IUPAC Recommendations 2001)

2001 ◽  
Vol 73 (11) ◽  
pp. 1749-1764 ◽  
Author(s):  
Antony N. Davies ◽  
Jörg Lambert ◽  
Robert J. Lancashire ◽  
Peter Lampen ◽  
Woody Conover ◽  
...  
Keyword(s):  
Experimental Data ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Pulse Sequence ◽  
Pulse Sequences ◽  
Resonance Spectroscopy ◽  
Data Content ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry ◽  
Nuclear Magnetic

In drawing up the specifications for a standard for multidimensional nuclear magnetic resonance spectroscopy (NMR) it became clear that the spectroscopic data content needed to be qualified by experimental condition information especially pertaining to the pulse sequences used to obtain the free induced decays or spectra. Failure to include this information not only severely inhibits the ability of subsequent data handling packages to work with the experimental data, but also makes interpretation of the final results virtually impossible.This paper has been produced in collaboration with the NMR spectrometer manufacturers in an attempt to get agreement on a definitive list of the most frequently used pulse sequence programs. The list includes entries where common agreement has been reached as to the acronym to name the experiment and the key instrument independent parameters needed to report concisely. It is not intended to restrict in any way the freedom of manufacturers or users to develop new and novel experimental pulse sequences, but should aid reporting of experimental data where the more common sequences are in use.

scholarly journals Conformational study of a series of 6-substituted 5,6,7,12-tetrahydrodibenzo[a,d]-cyclooctenes by nuclear magnetic resonance spectroscopy

1977 ◽  
Vol 55 (19) ◽  
pp. 3456-3463 ◽  
Author(s):  
Roger N. Renaud ◽  
John W. Bovenkamp ◽  
Robert R. Fraser ◽  
Jean-Louis A. Roustan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Variable Temperature ◽  
Resonance Spectroscopy ◽  
Proton Nmr Spectroscopy ◽  
Conformational Study ◽  
Methyl Derivative ◽  
Conformational Properties ◽  
Different Temperatures ◽  
Keto Derivative ◽  
Twist Boat

The conformational properties of seven 5,6,7,12-tetrahydrodibenzo[a,d]cyclooctenes bearing substituents at C-6 have been studied using variable temperature proton nmr spectroscopy. The position of the equilibrium between boat-chair (BC) and twist-boat (TB) conformers has been measured in several solvents. In contrast to the unsubstituted dibenzocyclooctene, appreciable amounts of TB conformer are present when C-6 is substituted by alkyl, hydroxy, or cyano substituents. Measurements at different temperatures showed the TB form to possess the greater entropy. Barriers to the BC → TB interconversion were determined by coalescence studies, using both approximate and complete line shape methods. Barriers ranged from 10.1 kcal/mol for the 6-keto derivative to 16.7 kcal/mol for the 6-hydroxy-6-methyl derivative.

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