Studies Relating to Aziridine Antitumor Antibiotics. Part II. 13C and 1H Nuclear Magnetic Resonance Spectra of Mitomycin C and Structurally Related Streptonigrin

1974 ◽  
Vol 52 (12) ◽  
pp. 2331-2336 ◽  
Author(s):  
J. William Lown ◽  
Asher Begleiter
Keyword(s):  
Mitomycin C ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Antitumor Antibiotic ◽  
Antitumor Antibiotics ◽  
Nuclear Magnetic Resonance Spectra ◽  
1H Nuclear Magnetic Resonance ◽  
The Common

Double irradiation experiments in the 100 MHz n.m.r. spectrum of mitomycin C allowed determination of vicinal coupling constants which provide information on the conformation of the antibiotic in solution. The natural abundance 13C spectrum and comparison with selected model compounds allowed assignment of the carbon resonances of mitomycin C. The 13C chemical shifts of the quinone ring carbons in mitomycin C have a bearing on the proposed stabilization in vivo. Similar studies on the antitumor antibiotic streptonigrin bearing the common aminoquinone moiety gave indications of conjugative interactions similar to those established for mitomycin C.

An 1H nuclear magnetic resonance study of derivatives of 3-hydroxy-12,13-epoxytrichothec-9-enes

1987 ◽  
Vol 65 (9) ◽  
pp. 2254-2262 ◽  
Author(s):  
Marc E. Savard ◽  
Barbara A. Blackwell ◽  
Roy Greenhalgh
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Chair Conformation ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Substitution Pattern ◽  
Nuclear Magnetic Resonance Spectra ◽  
1H Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The 250-MHz 1H nuclear magnetic resonance spectra of 36 natural and synthetic trichothecenes have been analyzed and the chemical shifts as well as the vicinal and long-range coupling constants determined. Knowledge of the 16-CH3 chemical shift enables the substitution pattern of the A ring to be defined. Similarly, oxygenation in the C ring results in easily identifiable resonances. The J2,3 and J3,4 values define the configuration of substituents at C-3 and C-4, while the configuration at C-7 and C-8 can be defined by the J7,8, J7α,11, and J7β,15 values. The trichothecene ring system adopts the most stable A-half-chair, B-chair conformation in solution. The correlations obtained allow easy structural determination of unknown trichothecenes.

Gradient-Enhanced Inverse-Detected NMR Techniquesfor Determination of 1H-15N Coupling Constants in 2,2-Dimethylpenta-3,4-dienal Derivatives

1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Multiple Bond ◽  
Coupling Constants ◽  
Single Quantum ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
Heteronuclear Coupling

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

THE ANALYSIS OF NUCLEAR MAGNETIC RESONANCE SPECTRA: III. PYRIDINE AND DEUTERATED PYRIDINES

1957 ◽  
Vol 35 (12) ◽  
pp. 1487-1495 ◽  
Author(s):  
W. G. Schneider ◽  
H. J. Bernstein ◽  
J. A. Pople
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Calculated Spectrum ◽  
Proton Resonance ◽  
Nuclear Magnetic Resonance Spectra ◽  
Spin Coupling Constants

The proton resonance spectra of pyridine, 2,6-pyridine-d2, 3-pyridine-d1, and 4-pyridine-d1 have been obtained for the pure liquids under conditions of high resolution. The spectra have been analyzed as proton groupings of AB2X2, AB2, perturbed ABX, and B2X2 respectively. The spin-coupling constants obtained from analysis of the simpler spectra of the deuterated molecules were used to suggest trial solutions for the analysis of the complicated AB2X2 spectrum of pyridine. A final set of chemical shifts and spin-coupling constants derived for pyridine give satisfactory agreement between the observed and calculated spectrum.

The High Resolution NMR Spectra of Pesticides. III. The Carbamates

1970 ◽  
Vol 53 (1) ◽  
pp. 157-179 ◽  
Author(s):  
L H Keith ◽  
A L Alford
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Hindered Rotation ◽  
Solvent Dependence ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Proton Resonances

Abstract The high resolution nuclear magnetic resonance spectra of 35 carbamate pesticides and a major metabolite of one pesticide are discussed. The chemical shifts and coupling constants are tabulated and reproductions of the more complex or unusual spectra are included. A concentration and solvent dependence of both the NH-proton and the NCH3-proton resonances of an N-monosubstituted carbamate is discussed. Hindered rotation is observed in the N,N-dimethylcarbamates, the thiolcarbamates and the dithiocarbamates, but not in the N-methylcarbamates.

scholarly journals Carbon-13 nuclear magnetic resonance spectra of oxazoles

1979 ◽  
Vol 57 (23) ◽  
pp. 3168-3170 ◽  
Author(s):  
Henk Hiemstra ◽  
Hendrik A. Houwing ◽  
Okko Possel ◽  
Albert M. van Leusen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Coupling ◽  
Nuclear Magnetic Resonance Spectra ◽  
C Nmr ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 13C nmr spectra of oxazole and eight mono- and disubstituted derivatives have been analyzed with regard to the chemical shifts and the various carbon–proton coupling constants of the ring carbons. The data of the parent oxazole are compared with thiazole and 1-methylimidazole.

Studies related to antitumor antibiotics. Part XXIV. High field 1H nmr analysis and conformations of saframycins A and C

1981 ◽  
Vol 59 (20) ◽  
pp. 2945-2952 ◽  
Author(s):  
J. William Lown ◽  
Alummoottil V. Joshua ◽  
Hsiao-Hsiung Chen
Keyword(s):  
High Field ◽  
Chemical Shifts ◽  
Molecular Geometry ◽  
Coupling Constants ◽  
Cytotoxic Action ◽  
Antitumor Antibiotics ◽  
Dna Templates ◽  
H Nmr ◽  
Proton Chemical Shifts ◽  
Unambiguous Assignment

A detailed analysis of the high field (400 MHz) 1H nmr spectra of the basic antitumor antibiotics saframycin A and C in CDCl3, C6D6, and in aqueous DMSO solutions has been carried out. Selective double irradiation experiments permitted the unambiguous assignment of all the proton chemical shifts and coupling constants. Consideration of the magnitudes of the latter together with specific nOe experiments permits assignment of molecular geometry and average conformations in solution. Selective shifts occurring in DMSO–D2O solutions upon addition of CF3COOD identified the 12-N atom as the site of protonation which result bears directly on the acid promoted binding of these antibiotics to DNA templates as part of their cytotoxic action.

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