FORMATION OF DIASTEREOISOMERIC ORTHOACETATES OF D-MANNOSE: N.M.R. SPECTRAL EVIDENCE

1963 ◽  
Vol 41 (2) ◽  
pp. 399-406 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Acid Hydrolysis ◽  
Chemical Shifts ◽  
Isomer Ratio ◽  
Methyl Group ◽  
Major Isomer ◽  
Spectral Evidence ◽  
Ratio Data ◽  
Nuclear Magnetic

Diastereoisomeric 1,2-orthoacetates of D-mannose are formed under conditions of the Königs–Knorr synthesis. This is shown by the isolation of two crystalline isomers of β-D-mannose 1,2-(benzyl orthoacetate), and also by examination of the nuclear magnetic resonance (n.m.r.) spectra of several D-mannose orthoacetates. The diastereoisomers show notable differences in respective chemical shifts for the C-methyl and other protons and these variations, together with isomer-ratio data, suggest that the major isomer of a given pair possesses the configuration in which the C-methyl group is endo- and the OR group is exo-. On acid hydrolysis the orthoacetates yield mainly 2-O-acetyl-D-mannose, the structure of which is confirmed by n.m.r. spectral evidence.

A Study of the Proton Nuclear Magnetic Resonance Spectra of Aryl and Mono- and Disubstituted N-Methylazoles

1973 ◽  
Vol 51 (14) ◽  
pp. 2315-2322 ◽  
Author(s):  
Richard Noel Butler
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Structural Characteristics ◽  
Proton Nuclear Magnetic Resonance ◽  
Methyl Group ◽  
Nuclear Magnetic Resonance Spectra ◽  
Azole Ring ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Proton n.m.r. spectra of 111 substituted azoles are compared. The influence of the azole ring on the chemical shifts of substituent phenyl protons is discussed. A correlation between N-methyl chemical shifts and the structural characteristics of the N-methyl group in mono- and disubstituted azoles is noted.

Nuclear magnetic resonance studies on the configurations and conformations of heterocyclic nitrosamines

1968 ◽  
Vol 46 (17) ◽  
pp. 2827-2833 ◽  
Author(s):  
Y. L. Chow ◽  
C. J. Colón
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Methyl Group ◽  
Magnetic Resonance Studies ◽  
Rigid System ◽  
Nuclear Magnetic Resonance Spectra ◽  
Equatorial Proton ◽  
Configuration And Conformation ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra of various heterocyclic nitrosamines were studied in solution. A qualitative view of the long-range diamagnetic effects of a nitrosamino group is advanced and correlated with the chemical shifts of α-equatorial protons and the methyl group in those nitrosamines possessing a preferred conformation or a rigid system. The use of this correlation to decide the configuration and conformation of heterocyclic nitrosamines is discussed. A large chemical shift difference (ca. 3 p.p.m.) between a cis α-axial and a cis α-equatorial proton was noted.

Carbon-13 nuclear magnetic resonance examination of naphthalene derivatives. Assignments and analysis of substituent chemical shifts

1977 ◽  
Vol 42 (14) ◽  
pp. 2411-2418 ◽  
Author(s):  
William Kitching ◽  
Maxwell Bullpitt ◽  
David Gartshore ◽  
William Adcock ◽  
T. C. Khor ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Magnetic Resonance Examination ◽  
Naphthalene Derivatives ◽  
Nuclear Magnetic

Nuclear Magnetic Resonance Chemical Shifts of some Monosubstituted Isothiazoles

1975 ◽  
Vol 53 (4) ◽  
pp. 596-603 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Thomas R. Clem ◽  
Edwin D. Becker
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Charge Densities ◽  
Monosubstituted Benzenes ◽  
Proton Chemical Shifts ◽  
Nuclear Magnetic

Carbon-13 and proton chemical shifts have been measured for several monosubstituted isothiazoles. Substituent effects upon these chemical shifts are compared with those observed for monosubstituted benzenes, pyridines, and thiophenes. In general the observed substituent effects in the isothiazoles and thiophenes closely parallel one another. Correlations between the observed carbon-13 Chemical shifts and CNDO/2 calculated charge densities are examined.

Studies of specifically fluorinated carbohydrates. Part I. Nuclear magnetic resonance studies of hexopyranosyl fluoride derivatives

1969 ◽  
Vol 47 (1) ◽  
pp. 1-17 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville ◽  
N. S. Bhacca
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Angular Dependence ◽  
Chemical Shifts ◽  
Relative Orientation ◽  
Coupling Constants ◽  
Pyranose Ring ◽  
Spectral Parameters ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

A detailed study has been made of both the 1H and 19F nuclear magnetic resonance (n.m.r.) spectra of a series of hexopyranosyl fluoride derivatives. Some of the 1H spectra were measured at 220 MHz. The 1H spectral parameters define both the configuration and the conformation of each of these derivatives. Study of the 19F n.m.r. parameters revealed several stereospecific dependencies. The 19F chemical shifts depend upon, (a) the orientation of the fluorine substituent with respect to the pyranose ring and, (b) the relative orientation of other substituents attached to the ring; for acetoxy substituents, these configurational dependencies appear to be additive. The vicinal19F–1H coupling constants exhibit a marked angular dependence for which Jtrans = ca. 24 Hz whilst Jgauche = 1.0 to 1.5 Hz for [Formula: see text] and 7.5 to 12.6 Hz for [Formula: see text] The geminal19F–1H couplings depend on the orientation of the substituent at C-2; when this substituent is equatorial JF,H is ca. 53.5 Hz and when it is axial the value is ca. 49 Hz.

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