Conformational Studies of Substituted Trimethylene Sulfites by Proton Magnetic Resonance

1972 ◽  
Vol 50 (4) ◽  
pp. 521-527 ◽  
Author(s):  
Gordon Wood ◽  
G. W. Buchanan ◽  
M. H. Miskow
Keyword(s):  
Dipole Moment ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Shift Reagent ◽  
Coupling Constants ◽  
Considerable Degree ◽  
Conformational Studies ◽  
Alkyl Derivatives

Proton n.m.r. chemical shifts and coupling constants are reported for trimethylene sulfite and 10 alkyl derivatives in CCl4. Data are discussed in terms of possible chair and non-chair conformations and results are compared with those from dipole moment studies. The shift reagent Eu(dpm)3 is used to aid configurational assignments. Conclusions from n.m.r. and dipole moments are consistent and indicate that several of the sulfites exist to a considerable degree in non-chair conformations.

Protonenresonanz-Spektroskopie ungesättigter Ringsysteme I

1965 ◽  
Vol 20 (10) ◽  
pp. 948-956 ◽  
Author(s):  
Harald Günther
Keyword(s):  
Magnetic Resonance ◽  
Concentration Dependence ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Electron System ◽  
Coupling Constants ◽  
Resonance Signal ◽  
Aromatic Character ◽  
Additional Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of 1.6-methano- and 1.6-oxido-cyclodecapentaene are described and analyzed in terms of chemical shifts and coupling constants. The results are discussed in connection with the structure and possible aromatic character of these compounds. Measurements of the concentration dependence of the chloroform resonance signal in solutions of both compounds give additional support for the presence of a delocalized 10 π-electron system.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. V. Diazanaphthalenes

1965 ◽  
Vol 18 (5) ◽  
pp. 707 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Direct Calculation ◽  
Coupling Constants ◽  
Dilute Solutions ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the four isomeric diazanaphthalenes, quinoxaline, phthalazine, quinazoline, and cinnoline, all as dilute solutions in carbon tetrachloride and acetone, have been investigated at 100 Mc/s. The chemical shifts and coupling constants have been obtained by direct calculation or, where appropriate, by an iterative procedure. Long-range coupling constants between protons separated by five and six bonds have been observed.

Application of Carbon-13 Nuclear Magnetic Resonance to Conformational Analysis of Trimethylene Sulfites

1973 ◽  
Vol 51 (22) ◽  
pp. 3746-3751 ◽  
Author(s):  
Gerald W. Buchanan ◽  
J. B. Stothers ◽  
Gordon Wood
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Dipole Moment ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Chemical Shifts ◽  
Ring Carbon ◽  
Alkyl Derivatives ◽  
Nuclear Magnetic

Carbon-13 n.m.r. chemical shifts are reported for trimethylene sulfite, 10 alkyl derivatives, and a related 1,3,2-dioxathiane. Data are discussed in terms of possible chair and twist conformations and in some cases the data permit definitive conformational assignments. Results are compared with previous conclusions based on proton n.m.r. and dipole moment measurements. The orientation of the S=O group is shown to have a very pronounced influence on the C-4 and -6 ring carbon shieldings.

Proton magnetic resonance spectra of indolizine and its methyl derivatives and aza analogues

1964 ◽  
Vol 17 (10) ◽  
pp. 1128 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan ◽  
LM Jackman ◽  
QN Porter ◽  
GR Underwood
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Methyl Derivatives ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of indolizine, indolizine-1,3-d2, 1- and 2-methylindolizine, 2,3-, 2,5-, 2,6-, and 2,7-dimethylindolizine and 1-, 2-, and 3-azaindolizine have been determined at 100 and/or 60 Mc/s. Unequivocal assignments have been made to all protons and the coupling constants and chemical shifts for indolizine and its aza analogues have been obtained by an iterative procedure. Long-range coupling constants involving protons separated by five and six bonds have been observed.

A Proton Magnetic Resonance Study of the Influence of Base Ionization on the Conformation of Pseudouridine

1972 ◽  
Vol 50 (7) ◽  
pp. 766-774 ◽  
Author(s):  
Roxanne Deslauriers ◽  
Ian C. P. Smith
Keyword(s):  
Hydrogen Bond ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Coupling Constants ◽  
Hydroxyl Group ◽  
Basic Solution ◽  
Hydroxymethyl Group ◽  
Ultraviolet Spectra

The proton magnetic resonance spectra of alkaline deuterium oxide solutions of α-pseudouridine (α-ψ), β-pseudouridine (β-ψ), and 1-(β-D-ribofuranosyl)-cyanuric acid (β-CAR) are analyzed to explore the possibility that conformational changes are responsible for the unusual ultraviolet spectra of β-ψ at high pH. The largest change in ribose ring conformation due to increased alkalinity is observed in β-ψ; the ribose ring, although interconverting between various puckered forms, shows a slight preference for the 2′-endo and 3′-exo conformations. There is also a preference by α-ψ and β-ψ for the gauche-gauche rotamers about the exocyclic C4′–C5′ bond; this preference is not shown by β-CAR. No change occurs in the chemical shifts of the protons of α-ψ and β-ψ on going from neutral or acidic to basic solution. Increasing temperature to 60 °C causes no significant change in either coupling constants or chemical shifts. Comparison of chemical shifts observed in β-ψ with those found in β-CAR leads us to believe that the base remains in the anti conformation with respect to the ribose ring and is therefore incapable of forming a hydrogen bond with the exocyclic hydroxyl group as had been postulated previously to explain anomalous ultraviolet spectral data. A weak hydrogen bond between the 5′-hydroxymethyl group and the 5–6 double bond remains as a plausible explanation for the unusual ultraviolet spectra.

Determination of the molecular conformation of uridine in aqueous solution by proton magnetic resonance spectroscopy. Comparison with β-pseudouridine

1970 ◽  
Vol 48 (18) ◽  
pp. 2866-2870 ◽  
Author(s):  
Barry J. Blackburn ◽  
Arthur A. Grey ◽  
Ian C. P. Smith ◽  
Frank E. Hruska
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Molecular Conformation ◽  
Chemical Shifts ◽  
Proton Magnetic Resonance Spectrum ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Resonance Spectroscopy ◽  
Proton Coupling ◽  
Anti Conformation

A complete analysis of the 220 MHz proton magnetic resonance spectrum of aqueous uridine is reported. From the data a model for the molecular conformation is presented and compared with that of β-pseudouridine. It is concluded that in both compounds the ribose rings are in rapid equilibrium between classical puckered structures. The temperature-independence of the ribose proton coupling constants and chemical shifts suggests that all the conformers involved in this equilibrium have very similar energies. Both compounds exhibit a preference for the gauche–gauche rotamer about the exocyclic 4′—5′ bond; this conclusion is shown to be independent of the parameters in the Karplus equation or the energy minima chosen for the rotamers. The anti conformation of the uracil base is shown to exist in both compounds. It is proposed that the special structural significance of β-pseudouridine in transfer RNA must be due to the potential hydrogen bond that may be formed by the nitrogen atom at position one in uracil.

A Proton Magnetic Resonance Study of the Ultraviolet Photoproduct of d(TpT) in Aqueous Solution

1975 ◽  
Vol 53 (8) ◽  
pp. 1193-1203 ◽  
Author(s):  
Frank E. Hruska ◽  
Donald J. Wood ◽  
Kelvin K. Ogilvie ◽  
James L. Charlton
Keyword(s):  
Aqueous Solution ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Magnetic Resonance Study ◽  
Parent Molecule ◽  
Terminal Fragment ◽  
Proton Magnetic Resonance Study ◽  
Cyclobutane Ring

The p.m.r. data of d(TpT) and its predominant u.v. photoproduct d(T[p]T) in aqueous solution are compared. The data are consistent with the presence of a cis-syn cyclobutane ring in d(T[p]T). Consideration of the H1′ chemical shifts leads to the conclusion that changes in the sugar–base torsion angle of both nucleotide fragments of the parent molecule are required to bring the thymine bases into alignment for photodimerization. The coupling constants indicate that the conformation of the 5′-terminal fragment is only slightly affected by the cyclobutane ring formation. Photodimerization brings about a distortion of the sugar pucker in the 3′-terminal fragment. In this fragment both the gauche-gauche and gauche-trans conformers are significantly populated whereas the trans-gauche form is excluded.

CYCLOHEXANE COMPOUNDS: VI. NUCLEAR MAGNETIC RESONANCE SPECTRA OF SOME DERIVATIVES OF THE STEREOISOMERIC 3-BROMO-1,2-CYCLOHEXANEDIOLS AND THE 2-BROMO-1,3-CYCLOHEXANEDIOLS

1966 ◽  
Vol 44 (7) ◽  
pp. 775-780 ◽  
Author(s):  
R. A. B. Bannard
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Angular Distortion ◽  
Order Analysis ◽  
First Order ◽  
Nuclear Magnetic Resonance Spectra ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

First-order analysis of the 60 Mc.p.s. proton magnetic resonance spectra of 1α-methoxy-2β-acetoxy-3α-bromocyclohexane, 1α-methoxy-2α-acetoxy-3β-bromocyclohexane, 1α-methoxy-2β-bromo-3α-acetoxycyclohexane, 1α-methoxy-2α-bromo-3β-acetoxycyclohexane, and the corresponding diol diacetates confirmed the stereochemical interrelationships of substituents which were assigned previously on chemical grounds, and demonstrated that the compounds exist in chair conformations. The chemical shifts of the methoxy methyl and acetoxy methyl protons did not provide reliable criteria for the assignment of conformations to these substituents in this series. The coupling constants of the methine protons followed, in general, the pattern predicted by the Karplus equation, and the smaller J2,3 values observed in the cis,trans compounds relative to those in the trans,trans compounds are interpreted mainly on the basis of conformational equilibration, upon which is superimposed a small dihedral angular distortion or a remote substituent orientational effect.

THE PROTON RESONANCE SPECTRA OF SOME SUBSTITUTED FURANS AND PYRROLES

1961 ◽  
Vol 39 (4) ◽  
pp. 905-914 ◽  
Author(s):  
R. J. Abraham ◽  
H. J. Bernstein
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Resonance ◽  
Spin Coupling Constants ◽  
Substituted Furans ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of some substituted furans and pyrroles have been analyzed for spin coupling constants and chemical shifts.The relative insensitivity of the spin coupling constants to the nature of the substituent makes it possible to estimate their values in the parent molecules furan and pyrrole. The magnitude of the spin coupling constants is correlated with the angles made by the CH bonds with the CC bonds of the ring.The chemical shifts are interpreted in terms of an effect due to the electronegativity of the substituent together with the effect due to conjugation with the ring.

A nuclear Overhauser effect difference study and a two-dimensional J proton magnetic resonance study of (6S)-prostaglandin I1

1981 ◽  
Vol 59 (10) ◽  
pp. 1449-1454 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Tom T. Nakashima
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Proton Resonances ◽  
Nuclear Overhauser

High-field nuclear Overhauser effect difference measurements allowed the assignment of the proton resonances for (6S)-prostaglandin I1 in phosphate buffer solutions. The two-dimensional J proton magnetic resonance experiments complemented these studies, as they also allowed the structure of several multiplets to be obtained when these multiplets are hidden by nearby resonances in a normal spectrum. The chemical shifts and coupling constants are compared with the data obtained previously for (6R)-prostaglandin I1.

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