Nuclear magnetic resonance characterization of the ring conformations of monosubstituted derivatives of 1,3-dioxa-5,6-benzocycloheptene

1983 ◽  
Vol 61 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. St-Amour ◽  
M. St-Jacques
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Steric Effects ◽  
Slow Exchange ◽  
Conformational Properties ◽  
Derivatives Of ◽  
Ring Conformations ◽  
Twist Boat

The conformational properties of 2-alkyl (Me, Et, i-Pr, and t-Bu) and 2-phenyl derivatives of 1,3-dioxa-5,6-benzocycloheptene (1) were studied by 13C dnmr. Analysis of slow exchange spectra at 100.6 MHz indicates that all derivatives except tert-butyl exist in an equilibrium of chair (major) and twist-boat (minor) conformations. Substituent effects on the position of the equilibrium are rationalized in terms of steric effects.

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.

The Carbon-13 Nuclear Magnetic Resonance Spectra of 2-Acetamido-2-deoxy-D-hexoses and some Specifically Deuteriated, O-Acetylated, and Phosphorylated Derivatives

1973 ◽  
Vol 51 (22) ◽  
pp. 3812-3819 ◽  
Author(s):  
D. R. Bundle ◽  
H. J. Jennings ◽  
Ian C. P. Smith
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Model Compounds ◽  
Initial Assignment ◽  
Nuclear Magnetic Resonance Spectra ◽  
Polysaccharide Antigens ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 13C n.m.r. spectra of the 2-acetamido-2-deoxy-D-hexoses and some 3-O-acetyl and 1-phosphate derivatives are assigned and discussed. To facilitate the interpretation of the spectra, an initial assignment of the resonances in the spectrum of 2-acetamido-2-deoxy-D-glucose was required. For this purpose, both the 3-2H and 4-2H derivatives of this acetamido-hexose were synthesized. These syntheses are reported together with those of 2-acetamido-3-O-acetyl-2-deoxy-D-glucose and 2-acetamido-2-deoxy α- and β-D-glucose-1-phosphate. These model compounds were used to study substituent effects related to the 2-acetamido-2-deoxy-D-hexose-containing polysaccharide antigens of N. meningitides.

Synthesis and properties of phenyl substituted derivatives of 2-phenyl-1,1,3,3-tetramethylguanidine

1987 ◽  
Vol 65 (3) ◽  
pp. 626-629 ◽  
Author(s):  
Przemyslaw Pruszynski
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phenyl Ring ◽  
Substituent Effects ◽  
Ultraviolet Spectrophotometry ◽  
Elemental Analyses ◽  
Reaction Constant ◽  
Substituent Constants ◽  
Derivatives Of

A series of 17 phenyl substituted derivatives of 2-phenyl-1,1,3,3-tetramethylguanidine was synthesized. The structure and purity of these compounds were checked by means of elemental analyses, mass spectrometry, ultraviolet spectrophotometry, and 1H nuclear magnetic resonance. The pKa values were determined and are discussed in terms of substituent effects using Hammett substituent constants. The Hammett reaction constant ρ = 1.84 ± 0.05 was found to be much lower for para and meta substituted compounds than for anilines, even though the phenyl ring is attached directly to the basic centre in both cases.

Substituted carbonyl derivatives of the Group VI transition metals. V. Complexes with tolyl-substituted Bis(diphenylarsino)methane ligands

1974 ◽  
Vol 27 (2) ◽  
pp. 401 ◽  
Author(s):  
JA Bowden ◽  
R Colton ◽  
Z Sztajer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Steric Effects ◽  
Group Vi ◽  
Carbonyl Derivatives ◽  
Derivatives Of ◽  
Nuclear Magnetic

Ligands of the type bis(ditoly1arsino)methane have been synthesized and their derivatives with hexacarbonylmolybdenum(0) prepared. Nuclear magnetic resonance and infrared spectroscopy have been used to determine the stereochemistry of the complexes and also to study steric effects within the molecules.

Sign in / Sign up

Export Citation Format

Share Document