Hydroxyl proton resonances of methyl 4,6-O-benzyIidene-α- and β-D-glucopyranosides and their derivatives in dimethyl sulfoxide solution

1977 ◽  
Vol 55 (1) ◽  
pp. 141-144 ◽  
Author(s):  
Yôtaro Kondo ◽  
Keisuke Kitamura
Keyword(s):  
Magnetic Resonance ◽  
Dimethyl Sulfoxide ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Hydroxyl Group ◽  
Hydroxyl Proton ◽  
Dimethyl Sulfoxide Solution ◽  
Vicinal Diols ◽  
Proton Resonances ◽  
Derivatives Of

Proton magnetic resonance spectra of methyl 4,6-O-benzylidene-α- and β-D-glucopyranosides (1 and 10) and their mono-substituted derivatives are determined in dimethyl sulfoxide solution. Assignments of the hydroxyl group resonances of 1 and 10 are confirmed by means of INDOR techniques. It is shown that the position of the hydroxyl substituent of the mono-substituted derivatives of 1 and 10 can be determined by using the coupling constants JH—C—O—H. It is proposed that the vicinal diols of 1 and 10 give 1:1 associations with dimethyl sulfoxide molecules, and the C—H and O—H bonds at position 2 of the mono-substituted derivatives of 1 are approximately anti.

A proton magnetic resonance determination of the small rotational barriers about the C—Si bond in phenyl derivatives of chloro and methyl silanes

1977 ◽  
Vol 55 (3) ◽  
pp. 557-561 ◽  
Author(s):  
William J. E. Parr ◽  
Ted Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Low Energy Conformations

The long-range spin–spin coupling constants between protons bonded to silicon and ring protons in C6H5SiH3, C6H5SiH2Cl, C6H5SiH2CH3, C6H5SiHCl2, and C6H5SiH(CH3)2 are determined from the proton magnetic resonance spectra of benzene solutions. A hindered rotor treatment of the barrier to internal rotation about the C—Si bond, in conjunction with the coupling constants over six bonds, allows the deduction of the low-energy conformations for C6H5SiH(CH3)2 and for C6H5SiHCl2, as well as of barriers of 1.0 ± 0.2 kcal/mol. The approach becomes less reliable for C6H5SiH2CH3 and for C6H5SiH2Cl and, particularly for the latter compound, the derived barrier is very likely an upper limit only. Ab initio molecular orbital calculations of the conformational energies are reported for C6H5SiH3, C6H5SiH2Cl, and for C6H5SiHCl2.

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.

Proton magnetic resonance spectra of vinylmetallic compounds. Part I. Tetravinyl and triphenylvinyl derivatives of Group IVB elements

1968 ◽  
Vol 46 (14) ◽  
pp. 2373-2384 ◽  
Author(s):  
Seán Cawley ◽  
Steven S. Danyluk
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Phenyl Group ◽  
Coupling Constants ◽  
Multiple Quantum ◽  
Low Field ◽  
Diamagnetic Anisotropy ◽  
Vinyl Group ◽  
Derivatives Of ◽  
Magnetic Resonance Spectra

A study has been made of the proton magnetic resonance spectra for all of the Group IVB derivatives of the series MVi4 and [Formula: see text]([Formula: see text] = phenyl group and Vi = vinyl group). The spectra were measured at 60 MHz as accurately as possible and the assignment of transitions was checked with a variety of supplemental aids including double irradiation, multiple quantum transitions, and medium effects Final, accurate spectral parameters were derived using both iterative and exact computational methods for solution of the three-spin problem Excellent agreement was obtained between the sets of parameters determined by the two methodsThe chemical shifts for both series of compounds display a number of characteristic trends of which the most notable is a displacement of the vinyl proton signals to low field with increasing atomic number of the M atom In each series the largest shift change is noted in going from the carbon to the silicon derivative These deshieldings have been attributed to the enhanced possibility of dπ–pπ interaction between the central M atom and the vinyl group in higher members of the series Marked changes are also the internal shifts of the vinyl protons down both series of compounds It is concluded that these changes are principally due to the effects of the M—C bond diamagnetic anisotropy The trends in internal shifts can be satisfactorily reproduced by the dipole approximation using Δχ values of 4, 6, 8, 12, and 18 × 10−6 cm3 mole−1 for the C, Si, Ge, Sn, and Pb–carbon bonds respectivelyThe signals for the vinyl protons of the [Formula: see text] series are all located to low field relative to the MVi4 series This deshielding is satisfactorily accounted for by the effects of the phenyl ring diamagnetic anisotropy in the former seriesA linear correlation is observed between the sums of the coupling constants and the electronegativities, Em, of the central M atom for both series of compounds However, the ΣJ values for the [Formula: see text] series are all slightly lower than the corresponding sums for the MVi4 series, indicating that the electronegativity of the phenyl group is somewhat larger than for the vinyl groupA significant solvent and concentration dependence is only noted for compounds belonging to the [Formula: see text] series For example, the trans proton of [Formula: see text] shifts up-field by 4 Hz while the cis proton is displaced down-field by 4 Hz as the concentration of [Formula: see text] is increased to 50 mole % in carbon tetrachloride These changes have been interpreted on the basis of a solute–solute interaction scheme of the type proposed previously for phenyl proton shifts.

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.

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.

HYDROXYL PROTON MAGNETIC RESONANCE IN RELATION TO RING SIZE, SUBSTITUENT GROUPS, AND MUTAROTATION OF CARBOHYDRATES

1966 ◽  
Vol 44 (5) ◽  
pp. 539-550 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Magnetic Resonance ◽  
Dimethyl Sulfoxide ◽  
Proton Magnetic Resonance ◽  
Hydroxyl Proton ◽  
Magnetic Resonance Data ◽  
Resonance Properties ◽  
Furanose Form ◽  
Selective Deuteration ◽  
Hydroxyl Protons ◽  
Sugar Derivatives

Some magnetic resonance properties of hydroxyl protons are described for a variety of sugars and derivatives in dimethyl sulfoxide. Spectral information of this kind is shown to be useful, particularly for differentiating between certain types of interconvertible molecular species. For example, a reducing sugar may be characterized as pyranose or furanose depending upon whether it exhibits a resonance signal that can be ascribed to OH-4 or OH-5, respectively. According to the data obtained, α-D-glucose, α-D-xylose, β-D-arabinose, α-D-lyxose, and α- and β-D-ribose are pyranoses when freshly dissolved, whereas the 2,3-carbonate of D-mannose or D-lyxose is in a furanose form. Selective deuteration and spin decoupling were of primary importance in making some of the spectral assignments.Although arabinose, ribose, and galactose exist partly as furanoses in mutarotated aqueous solutions, their tendency to adopt the structure of the five-membered ring is much greater in dimethyl sulfoxide. Such variability may be due to an interplay of effects; for example, the furanose forms are relatively stable, but this property is masked in water by preferential solvent stabilization of the pyranose structures.Depending on the number and kinds of hydroxyl proton signals detected, it is possible to distinguish between cyclic and acyclic forms of certain sugar derivatives, as illustrated with hydrazones and with dialdehydes obtained by oxidative glycol scission. Hydroxyl proton magnetic resonance data are of value also for characterizing partially acetylated sugars.

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