Stereochemistry of Hexahydrocarbazoles; the Temperature-dependent Nuclear Magnetic Resonance Spectra of N-Acetyl Derivatives

1971 ◽  
Vol 49 (10) ◽  
pp. 1638-1643 ◽  
Author(s):  
Stewart McLean ◽  
U. O. Trotz ◽  
C. J. MacDonald ◽  
W. F. Reynolds ◽  
D. J. Wood
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Ring System ◽  
Rotational Isomerism ◽  
Conformational Mobility ◽  
Temperature Dependent ◽  
Nuclear Magnetic Resonance Spectra ◽  
Acetyl Group ◽  
Cis And Trans

The configuration of certain substituted hexahydrocarbazoles 2, of significance in connection with earlier work, has been established. A study of the temperature dependence of the n.m.r. spectra of N-acetyl derivatives, initiated with the intention of distinguishing between cis- and trans-fused isomers, has led to the conclusion that the distinction could not be made on this basis since all of the temperature-dependent phenomena, even in cases where the cis-fusion had been established by other means, could be associated with rotational isomerism of the N-acetyl group and no observable effects in the temperature range studied could be related to conformational mobility of the ring system. Nevertheless, the results obtained provide information of value and interest regarding the stereochemistry of hexahydrocarbazoles.

Nuclear magnetic resonance studies. III. Rotational isomerism of some C-glucosylflavonoid acetates

1965 ◽  
Vol 18 (5) ◽  
pp. 715 ◽  
Author(s):  
RA Eade ◽  
WE Hillis ◽  
DHS Horn ◽  
JJH Simes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Steric Hindrance ◽  
Chemical Shifts ◽  
Rotational Isomerism ◽  
Bulky Substituent ◽  
Temperature Dependent ◽  
Magnetic Resonance Studies ◽  
Rotational Isomers ◽  
Nuclear Magnetic

The temperature-dependent variations in the spectra of certain C-glucosyl-flavonoid acetates are attributed to the effect of steric hindrance of bulky substituent groups of the sugar and aromatic moieties on the rate of interconversion of the two rotational isomers present. The differences in the chemical shifts of the protons of the two isomers are attributed to differences in the orientation and position of the acetyl and phenyl groups.

Open chain nitrogen compounds. Part XIII. 1-Aryl-3-arylthiomethyl-3-methyltriazenes and 3-(arylazo)-1,3-thiazolidines

1988 ◽  
Vol 66 (10) ◽  
pp. 2487-2491 ◽  
Author(s):  
Keith Vaughan ◽  
Hartford W. Manning ◽  
Marcus P. Merrin ◽  
Donald L. Hooper
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Active Metabolite ◽  
Aqueous Acetone ◽  
Rotational Isomerism ◽  
Nitrogen Compounds ◽  
Open Chain ◽  
New Class ◽  
Nuclear Magnetic Resonance Spectra ◽  
Show Evidence

Reaction of 3-acetoxymethyl-1-aryl-3-methyltriazenes with sodium thiophenolate or thiocresolate in anhydrous dimethylformamide affords a new series of 3-arylthiomethyltriazenes (2), Ar-S-CH2-NMe-N=N-Ar′. These triazenes are remarkably labile in aqueous buffer and may be good pro-drugs for the active metabolite of the antitumour dimethyltriazenes. The reaction of arenediazonium fluoroborates with 1,3-thiazolidine in aqueous acetone affords a new series of N-arylazo-1,3-thiazolidines (4); the arylazothiazolidines represent a new class of triazene in which the N3 nitrogen is incorporated into a heterocyclic unit, in this case a 1,3-thiazolidine. Nuclear magnetic resonance spectra of the arylazothiazolidines show evidence for rotational isomerism of the exocyclic N2—N3 bond in the triazene moiety.

Stereochemical assignment of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols via oxazolidin-2-one derivatives

1987 ◽  
Vol 65 (4) ◽  
pp. 868-872 ◽  
Author(s):  
Antonio Delgado ◽  
David Mauleon ◽  
Cristina Minguillon ◽  
Miguel Feliz ◽  
Miquel A. Pericas ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chair Conformation ◽  
Stereochemical Assignment ◽  
Magnetic Resonance Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Conformationally Restrained ◽  
Cis And Trans ◽  
Theoretical Results ◽  
Nuclear Magnetic

The stereochemical assignment of cis- and trans-2-amino-1,2,3,4-tetrahydro-1-naphthalenols (1) can be performed by means of their conformationally restrained tricyclic tetrahydronaphtho[2,1-d]oxazol-2-one derivatives 2–6. Thus, 1H and 13C nuclear magnetic resonance data of compounds 2–6 reveal differences between the cis and trans stereoisomers that are independent of the nature and number of the aromatic substituents. Conformational analysis of compounds 2–6 has been performed from the LAOCOON/3 analysis of their nuclear magnetic resonance spectra and MNDO theoretical results, through the use of the Karplus–Altona equation. Whereas the trans compounds exist in a rigid half-chair conformation, a 1:1 equilibrium of two interconverting half-chair conformers is found for the cis derivatives.

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