Studies of Carbohydrate derivatives by nuclear magnetic double-resonance Part II. A determination of the signs of proton-proton coupling-constants of saturated and unsaturated carbohydrates

1968 ◽  
Vol 8 (3) ◽  
pp. 295-307 ◽  
Author(s):  
L.D. Hall ◽  
J.F. Manville
Keyword(s):  
Double Resonance ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Nuclear Magnetic

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

Concerning the extension of the J method for internal barriers to six-bond couplings to 19F in the 4-fluorophenyl fragment

1978 ◽  
Vol 56 (18) ◽  
pp. 2442-2446 ◽  
Author(s):  
Ted Schaefer ◽  
Werner Danchura ◽  
Walter Niemczura ◽  
James Peeling
Keyword(s):  
Ground State ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Side Chain ◽  
Fluorine Nucleus ◽  
Proton Proton ◽  
Proton Coupling ◽  
Carbon Carbon Bond ◽  
Internal Barriers

The long-range coupling constants over six bonds from the side-chain protons to the fluorine nucleus on the ring are extracted from the proton magnetic resonance spectra of p-fluorobenzyl cyanide, chloride, and bromide; of p-fluorobenzal chloride; and of p-fluoroisopropylbenzene. On the assumption that these couplings are transmitted via a σ–π mechanism, a hindered rotor treatment yields the barriers to internal rotation about the carbon–carbon bond which attaches the substituent to the benzene ring. These barriers, when compared to those derived from the analogous proton–proton coupling constants, apparently are accurate enough for the determination of ground state conformations and for a rough assessment of the energetics of conformational interconversions.

The Proton–Proton and Proton–Carbon-13 Spin–Spin Coupling Constants in 1,3-Dioxole and Bis-1,3-dioxolyl. Conformational Dependence

1975 ◽  
Vol 53 (18) ◽  
pp. 2734-2741 ◽  
Author(s):  
Ted Schaefer ◽  
Kalvin Chum ◽  
David McKinnon ◽  
M. S. Chauhan
Keyword(s):  
Double Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dihedral Angles ◽  
Proton Proton ◽  
Proton Coupling ◽  
Vicinal Proton ◽  
Karplus Relationship ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The carbon-13 satellite peaks in the proton magnetic resonance spectra of 1,3-dioxole and bis-1,3-dioxolyl are analyzed under single and double resonance conditions to yield the signs and magnitudes of proton–proton coupling constants over three, four, and five bonds, and of proton–carbon-13 coupling constants over one, two, and three bonds. The conformational behavior of bis-1,3-dioxolyl contrasts sharply with that of analogous sym-tetrasubstituted ethane derivatives. It is indicated that the two-bond proton–carbon-13 coupling in the ethanic fragment can be used for conformational analysis in a manner similar to vicinal proton–proton couplings. The vicinal three-bond proton–carbon-13 couplings are given for dihedral angles of 180 and 120° and their relative magnitudes are as expected from a Karplus relationship. The two-bond proton–carbon-13 coupling in the olefinic fragment is, at 20.0 Hz, the largest coupling known for such a bond.

2 J HH -resolved HSQC: Exclusive determination of geminal proton-proton coupling constants

2017 ◽  
Vol 282 ◽  
pp. 18-26 ◽  
Author(s):  
Núria Marcó ◽  
Pau Nolis ◽  
Roberto R. Gil ◽  
Teodor Parella
Keyword(s):  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton

Transoid Homoallylic Proton-Proton Coupling Constants

1989 ◽  
Vol 42 (5) ◽  
pp. 659 ◽  
Author(s):  
M Barfield ◽  
RJ Spear ◽  
S Sternhell
Keyword(s):  
Angular Dependence ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Mo Calculations ◽  
Proton Proton ◽  
Proton Coupling ◽  
Tentative Assignment ◽  
Single Compound ◽  
Derivatives Of

Transoid homoallylic coupling constants (5JH,H) for six compounds (5,10-dihydroindeno[2,1-alindene and confertifolin derivatives) of fixed stereochemistry were determined and compared with calculated values. Magnetic equivalence limited discrete determination of 5Jtrans and 5Jcis to three of these compounds. The single compound where unequivocal assignment could be made revealed 5Jtrans > 5Jcis; this was supported in two other compounds by tentative assignment. Changes in the magnitude of the couplings suggested that substantial substituent effects may be operative. INDO-MO calculations correctly predicted the angular dependence but incorrectly predicted 5Jcis > 5Jtrans.

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