Wiley
0030-4921
Cơ quản chủ quản: N/A
Các bài báo tiêu biểu
13C n.m.r. spectra of steroids —a survey and commentary
Tập 9 Số 8 - Trang 439-464 - 1977
AbstractThe literature on 13C n.m.r. examinations of steroids has been reviewed
and the shielding data for over 400 examples are tubulated. The assignments for
each compound have been considered and, where necessary, revised in the light of
more recent evidence and for consistency throughout each series. The methods
available for assignments are reviewed and, in many cases, illustrated with
specif...
Theoretical and empirical calculations of the carbon chemical shift in terms of the electronic distribution in molecules
Tập 7 Số 1 - Trang 2-17 - 1975
AbstractThe principles of the theoretical calculations of the carbon atom
screening constant are reviewed. The Independent Electron, SCFMO and Valence
Bond formulae are briefly discussed, and the relative importance of the
different terms involved in an approximate decomposition of σ13C are pointed
out. The variations of the excitation energy ΔE, the mean distance between the
nucleus and 2p elect...
Stereochemical aspects of proton chemical shifts. III—Configurational assignments in pentacyclic systems without recourse to a karplus equation
Tập 7 Số 7 - Trang 345-348 - 1975
AbstractIt is shown that in contrast to the use of coupling constants, chemical
shift criteria may lead to unambiguous structural elucidations in
pseudorotational frameworks (pentacycles, heptacycles, etc.).
The 1H, 13C and 31P NMR spectra of EZ pairs of some phosphorus substituted alkenes
Tập 15 Số 1 - Trang 37-42 - 1981
AbstractThe olefins Ph2P(X)CHCHR [X=lone pair, O, S, Ch3I; RCh3, ph, P(X)ph2]
have been prepared and their 1H, 13C and 31P NMR spectra measured. trans
3J[P(IV)C] (range 18.3–25.7 Hz) is greater than cis 3J[P(IV)C] (range 6.9–11 Hz)
but this relationship does not hold for P(III) compounds. In the 31P spectra the
E isomer absorbs to higher field than the Z isomer for P(III) and P(IV)
compounds. Th...
Détermination des Axes Propres et des Valeurs Principales du Tenseur ḡ dans deux Radicaux Libres Nitroxydes par Étude de Monocristaux
Tập 5 Số 1 - Trang 47-52 - 1973
AbstractLa structure de la phase basse température du radical nitroxyde
tétraméthyl‐2,2,6,6 pipéridine oxyle‐1 (Tanane) a été déterminée. Ce radical
libre est isomorphe du tétraméthyl‐2,2,6,6 pipéridinol‐4 oxyle‐1 (Tanol). Une
étude en résonance paramagnétique électronique de monocristaux a permis de
déterminer les valeurs principales et l'orientation des axes propres du tenseur
ḡ pour ces deux ra...
13C NMR spectra of benzofuroxan and related compounds
Tập 8 Số 3 - Trang 158-160 - 1976
AbstractThe 13C n.m.r. spectrum of benzofuroxan at −15°C is assigned on the
basis of selective decoupling experiments and by comparison with the 13C
chemical shifts of model compounds. The 13C spectra were also measured in
trifluoroacetic acid as a solvent. From the temperature dependence of the 13C
spectrum of benzofuroxan in CDCl3, a barrier of 14·0 ± 0·2 kcal mol−1 is
obtained for the degenerat...
1H and 13C NMR study of 8‐hydroxyquinoline and some of its 5‐substituted analogues
Tập 15 Số 3 - Trang 280-284 - 1981
Abstract1H and 13C NMR spectra of 8‐hydroxyquinoline (oxine) and its 5‐Me, 5‐F,
5‐Cl, 5‐Br and 5‐NO2 derivatives have been studied in DMSO‐d6 solution. The 1H
and 13C chemical shifts and proton–proton, proton–fluorine, carbon–proton and
carbon–fluorine coupling constants have been determined. The 1H and 13C chemical
shifts have been correlated with the charge densities on the hydrogen and carbon
a...
Conformational analysis of the tropane analogue of pethidine and related compounds by 1H NMR spectroscopy
Tập 6 Số 8 - Trang 441-444 - 1974
AbstractThe preferred solute conformation of ethyl
3α‐phenyltropane‐3β‐carboxylate hydrochloride, the tropane analogue of
pethidine, is shown to be a piperidine chair with an axial 3‐phenyl substituent
by analysis of its 1H NMR characteristics and spectral comparisons with model
compounds. Conformational studies of synthetic intermediates are also reported
and favoured boat forms identified for 3α...
Fast searching for identical 13C NMR spectra via inverted files
Tập 15 Số 2 - Trang 178-187 - 1981
AbstractInverted files of spectral features should be employed when searching
for identical or similar spectra. The efficiency of interescting the entries for
chemical shifts with a small deviation is very high for larger molecules and
incomplete spectra. A novel spectral code describing the spectral appearance in
hierarchical order (SAHO) facilitates the search for complete spectra with a
relativ...
Modelling of the alkyl environment effects on the 13C chemical shift
Tập 14 Số 4 - Trang 264-271 - 1980
AbstractUsing a topological parameter, λR, to characterize the effects of a
variable mono or polyalkyl environment, R, on widely varied types of 13C sites
gives rise to a homogeneous description of their chemical shifts over the entire
range of δ13C variation (220 ppm/TMS). The proposed model, δ13C=ωcλR+ηc
expresses the chemical shift in terms of this parameter together with the
sensitivity, ωc, o...