bluuebunny/crossref_metadata_2025_split huggingface dataset:
NMR studies on bridged polycyclic compounds: Spin system transitions due to induced solvent shifts
Authors: Ramey Kermit C. , Moriarty Robert M. , Gopal Harsh , Adams Timothy 
Published: May 2005

AbstractAn NMR study of some bridged bicyclo and tricyclo compounds yielded unusual spectra with respect to solvent effects and virtual coupling. As is the general case for most large polycyclic systems a complete analysis of the spectrum is not possible and the structural details derived from NMR are based on a partial analysis of the spectrum. If the accessible resonances correspond to protons adjacent to methylene groups, the resonance patterns and the chemical shifts may be strongly dependent upon solvent. For 6‐endo‐hydroxy, bicyclo[2.2.1]heptane‐2,endo‐carboxylic acid lactone (1), 6‐endo‐hydroxy, 2‐exo‐methyl‐bicyclo[2.2.2]octane‐2‐endo‐carboxylic acid lactone (2), and exo‐3,4,exo‐8,9‐diepoxy, endo‐tricyclo[5,2,1,02,6]decane (3), resonances for each fall in this class and the change induced by solvent are attributed to virtual coupling as well as a change in the overall splitting pattern.
NMR studies of substituted pyridines
Authors: Gerig J. T. , Reinheimer John D. 
Published: May 2005

AbstractProton magnetic resonance chemical shifts and coupling constants for a series of 2‐substituted‐5‐nitropyridines and 2‐substituted‐3‐nitropyridines, both in the free base and protonated forms, are reported. The substituents were chloro, bromo, iodo, and hydroxyl. The effect of the substituents on the chemical shifts are substantial but not unusual. The coupling constants are less sensitive to the nature of the substituent and are perturbed only slightly when the ring nitrogen is protonated. This latter observation is consistent with the results of LCAO‐MO calculations.
Chemical shifts in methylcyclohexane
Authors: Lambert Joseph B. , Takeuchi Yoshinobu 
Published: May 2005

AbstractIn order to determine the effect of a single methyl group on the chemical shifts of protons in a cyclohexane ring, methylcyclohexane‐1,2,3,3,5,5,‐d6 has been synthesized. The protons in the 4‐position and the 2,6‐equatorial protons are not significantly different from those in ring‐frozen cyclohexane. The 2,6‐axial protons, however, experience an up‐field shift of about 15 Hz from the position of the other axial protons. These observations are discussed in terms of the structure of methylcyclohexane.
Protonenresonanz‐Spektroskopische Untersuchungen am Acetyl‐cyclobutadien‐eisentricarbonyl. Ein Beitrag zur Kenntnis der Bindungsverhältnisse im Komplex Gebundenen Cyclobutadien
Authors: Brune Hans Albert , Hüther Hans , Wolf Rochus , Körber Ingo 
Published: May 2005

AbstractDas Protonenresonanz‐Spektrum des Acetyl‐cyclobutadien‐eisentricarbonyls wurde einschließlich aller beobachtbaren 13CH‐Kopplungskonstanten vermessen. Die Kopplungen warden zugeordnet und im Hinblick auf Molekülstruktur und Bindungsverhältnisse diskutiert. Auf Grund der Messungen kann die Struktur eines cyclisch‐konjugierten Diens mit alternierenden Doppel‐ und Eingachbindungen ausgeschlossen warden.
PMR studies of the deuteration and hydration of 4‐piperidones
Authors: Hassan M. M. A. , Casy A. F. 
Published: May 2005

AbstractPMR spectra of substituted 4‐piperidones in base and salt forms in D2O, water and other solvents are reported, and spectral characteristics interpreted in terms of equilibria between free ketone and 4,4‐dideuteroxy (or hydroxy) forms. It is shown that 1‐mono and 1,3‐disubstituted‐4‐piperidones exist extensively as the corresponding dideuteroxy (or hydrated) species in D2O (or H2O) provided the ring nitrogen atom is positively charged, and that 3‐substituents decrease the population of these forms. The facile D/H exchange of α‐protons in the piperidone bases is also demonstrated.
Solvent effects in NMR spectra induced by aromatic solvents in 1,4‐dioxanes, 1,3‐dioxolanes and in sulphur analogues
Authors: Alexandrou N. E. , Hadjimihalakis P. M. 
Published: May 2005

AbstractNMR solvent effects induced by aromatic solvents on some 1,4‐dioxanes, 1,3‐dioxolanes and on some sulphur analogue derivatives are reported. The shielding effect of the aromatic solvents is examined in respect to the structure of the solute.
Konformative Beweglichkeit Flexibler Ringsysteme—XIII: Untersuchungen mit Hilfe der Protonenresonanzspektroskopie die Konformation des Ungesättigten Siebenringes im Benzocyclohepten und in symmetrisch substituierten derivaten
Authors: Kabuß S. , Schmid H. G. , Friebolin H. , Faißt W. 
Published: May 2005

AbstractFür 4.4.6.6‐Tetradeuterium‐1.2‐benzocyclohepten‐(1) (1) und fünf Benzocyclo‐heptenderivate wurde PR‐specktroskopisch die Konformation des ungesättigten Siebenringes bestimmt. Bei allen untersuchten Verbindungen liegt bei −80° nur ein Konformeres in nachweisbarer Menge vor. Durch Auswertung PR‐spektroskopisch bestimmter Daten – Molekel‐Symmetrie, Kopplungskonstanten, chemische Verschiebungen – kann gezeigt werden, daß dieses Konformere Sesselform hat. Die freie Konformationsenthalpie der beiden anderen Konformeren mit Wannen‐ bzw. Twist‐Form des Siebenringes beträgt bei allen sechs Verbindungen mehr als 1,8 kcal/Mol.Mit den experimentellen Ergebnissen stimmen diejenigen von Modellrechnungen überein: Für die Molekeln des Benzocycloheptens sowie des 5.5‐Dimethylderivates (2) und der 4.4.6.6‐Tetramethylverbindung (4) wurde für die Sesselkonformation der niedrigste Energieinhalt berechnet; als zweitstabilste Konformation wurde bei 1 und 4 die Wanne, bei 2 hingegen die Twist‐Form ermittelt.
Proton magnetic resonance studies of tautomerism in substituted pyrimidines
Authors: Glasel Jay A. 
Published: May 2005

AbstractStudies of line width and chemical shift vs. temperature for amide and hydroxyl proton magnetic resonance signals from: barbituric acid, dialuric acid, parabanic acid, alloxan and alloxan monohydrate dissolved in anhydrous dimethyl sulfoxide‐d6 are reported. The behavior of the amide signals shows that, between 20 and 65°C, none of the compounds listed exhibits lactim‐lactam tautomerism. The amide proton resonance in uracil has also been investigated. The signal is a closely spaced, equal intensity, doublet due to the non‐equivalence of H(1) and H(3). Again, no evidence of tautomerism is observed. Activation energies for the hydroxyl resonances in dialuric acid and alloxan monohydrate indicate hydrogen bonding between solute and solvent. The results of simple LCAO‐MO calculations are in accord with the experimental conclusions concerning tautomeric equilibria.
Die Konformeren des 5,5‐Dimethyl‐3,7‐dithia‐1,2‐benzocycloheptens‐(1) und ihre Umwandlungen Konformative Beweglichkeit flexibler Ringsysteme—XV. Untersuchungen mit Hilfe der Protonenresonanzspektroskopie
Authors: von Bredow K. , Friebolin H. , Kabuß S. 
Published: May 2005

AbstractDie Temperaturabhängigkeit der Protonenresonanzen (PR) des 5.5‐Dimethyl‐3.7‐dithia‐1.2‐benzocycloheptens‐(1) wird beschrieben und diskutiert. Diese Verbindung liegt in zwei Konformeren mit unterschiedlicher Topographie des Siebenringes vor. Anhand der den Tieftemperatur‐spektren entnommenen Werten der chemischen Verschiebung der Signale geminaler Methylgruppen wird gezeigt, daß der Siebenring bei einem dieser Konformeren Sessel‐, beim anderen Twistform hat. Die freie Konformationsenthalpie des Twistkonformeren beträgt nur etwa 20 cal/Mol. Zwei konformative Umwandlungsprozesse können kinetisch verfolgt werden: Die Version zwischen Sessel‐ und Twist‐Konformationen und die Pseudorotation der Twist‐Konformationen. Die freie Aktivierungsenthalpie ΔGv≠ der Version berträgt 12,6 ± 0,1 kcal/Mol(bei − 12°C), die freie Aktivierungsenthalpie ΔGP≠ der Pseudorotation 8.3 ± 0.3 kcal/Mol (bei −95°C).
Etude par RMN de la Structure des Cyano‐2 Alcoyl‐2 Norbornenes‐5
Authors: Muller J. C. , Fleury J. P. , Scheidegger U. 
Published: May 2005

AbstractL'attribution de structure des deux isomères cyano‐2 alcoyl‐2 norbornène‐5 est possible grǎce aux données de la RMN. Une interprétation des spectres de ces dérivés bicycliques set donnée. Dans le cas des cyano‐2 méthyl‐2 norbornènes‐5 une confirmation de structure a pu ětre donnée par voie chimique (hydrolyse basique et iodolactonisation).
Carbon‐13 chemical shifts of α,β‐unsaturated acids
Authors: Lippmaa E. , Pehk T. , Andersson K. , Rappe C. 
Published: May 2005

AbstractCarbon‐13 spectra of 59 α,β‐unsaturated carboxylic acids have been measured. Large differential shieldings of ethylenic carbons in the cis and trans isomers of acrylic acid derivatives were found (altogether 15 isomeric Z‐ and E‐pairs of acids were investigated). The origin of differential shieldings is complex and both molecular ground states as well as changes in excited states appear to be involved. All measured 13C chemical shifts can be described by additive parameters that provide a straightforward new technique by which structural assignments can be made for a wide variety of isomeric mono‐, di‐ and tri‐ substituted α,β‐unsaturated acids.
The structure of trisformamidomethane in dimethyl sulphoxide‐d6, hexamethylphos‐phortriamide and trifluoroacetic acid
Authors: Armarego W. L. F. , Kobayashi Toshihiko 
Published: May 2005

AbstractThe PMR spectrum of trisformamidomethane in dimethyl sulphoxide‐d6 and hexamethyl‐phosphortriamide has been explained by postulating four major structures in solution: two rotamers and two structural isomers, all of which are stabilized by intramolecular hydrogen bonding to form six membered rings. The spectrum in trifluoroacetic acid is also described.
Analyse Conformationnelle en Serie Alcoylidene‐5 Dioxanne‐1,3
Authors: Desaulles Philippe , Fleury Jean‐Pierre 
Published: May 2005

AbstractUn certain nombre d'alcoylidène‐5 alcoyl‐2 dioxannes‐1,3 ont été étudiés par RMN. L'analyse des spectres permet de conclure à une conformation chaise prédominante de ces dérivés, le substituant alcoyle sur carbone 2 se plaçant en position équatorial. Pour les alcoylidène‐5 dioxannes‐1,3 non substitués sur carbone 2 il y a inversion rapide du cycle avec une barrière énergétique extrěmement faible.
High‐resolution nuclear magnetic resonance spectra of phenanthrenes–IV Phenyl derivatives of phenanthrene
Authors: Bartle K. D. , Bavin P. M. G. , Jones D. W. 
Published: May 2005

AbstractProton magnetic resonance spectra at 60 MHz are reported for 9, 9′‐biphenanthryl, 1‐phenylfluoranthene, 9‐benzylphenanthrene, 1‐, 4‐ and 9‐phenylphenanthrenes and 9‐methyl‐10‐phenylphenanthrene, all in CS2 solution. Approximate values of some of the chemical shifts and coupling constants were extracted from the overlapped and often collapsed AB, ABC ABCD and AA′BB′C (phenyl) spin systems. By comparison with data for phenanthrene itself, estimates have been made for the dihedral angle, θ, between the planes of the phenyl ring and the phenanthrene nucleus in phenylphenanthrenes. These lead, except for 9‐phenylphenanthrene for which the angle derived from H(10) by PMR is higher than UV suggests, to plausible values for θ: 90°, 75°, 40° and 45 to 60°, for 4‐phenyl, 9‐methyl‐10‐phenyl‐, 1‐ and 9‐phenylphenanthrenes, respectively.
Spectroscopic studies on N,N‐dimethylamides—I: Structure‐reactivity correlation for rotational barriers from a nuclear magnetic resonance study of p‐ and m‐substituted N,N‐dimethylbenzamides
Authors: Korver P. K. , Spaargaren K. , van der Haak P. J. , de Boer Th. J. 
Published: May 2005

AbstractRotational barriers in 21 p‐ and m‐substituted N,N‐dimethylbenzamides in CDCl3 as solvent have been determined using the intensity ratio method of Woodbrey. These data compare very well with values from the literature1 obtained with a total line shape analysis. From structure‐reactivity correlations evidence has been obtained for a relatively strong resonance interaction between the substituent in the aromatic ring and the partially double amide bond.
New evidence of the intrinsic chemical shift non‐equivalence
Authors: Dabrowski Janusz , Ejchart Andrzej , Biernacki Władysław 
Published: May 2005

AbstractCarbinols of the general formulae R·CHOH·C(NO2)Me2 exhibit increasing values of chemical shift non‐equivalence for the geminal methyl groups with rise of temperature. This phenomenon furnishes indirect evidence for the intrinsic non‐equivalence.
1H magnetic resonance spectroscopy of some substituted acetophenones
Authors: Bloxsidge J. , Jones J. R. , Marks R. E. 
Published: May 2005

AbstractMeasurements are reported on the nuclear magnetic resonance spectra of the acetyl protons of a series of substituted acetophenones. Although the extreme values of the chemical shifts, δ for the meta‐ and para‐ substituted compounds differ only by 0·2 units, the values themselves are linearly related to the Hammett substituent constants. No such relationship exists for the ortho‐substituted compounds. The magnitude of the chemical shift is independent of substrate concentration over a five‐fold variation.
Spectroscopic studies on olefins—III: NMR of cis‐ and trans‐ disubstituted olefins
Authors: Rummens F. H. A. , de Haan J. W. 
Published: May 2005

AbstractThe proton NMR spectra of four cis/trans pairs of 1,2‐disubstituted olefins have been analysed. The observed trends of the olefinic, vicinal and allylic proton‐proton coupling constants are discussed in terms of rehybridization at the sp2 carbon atoms. It is found that in these substances the trans‐allylic couplings are generally more negative than the cis‐allylic couplings contrary to Barfield's1 theoretical prediction but in agreement with some earlier experimental data. Steric hindrance between cisoid substituents is cited as the probable origin of this end related trends.
Dérivés Alléniques de l'Étain, du Plomb et du Mercure. Signes Relatifs des Constantes de Couplage Métal‐Proton á Travers Deux et Quatre Liaisons
Authors: Simonnin Marie‐Paule , Lequan Minh , Lecourt Marie‐José 
Published: May 2005

AbstractLes spectres de Dérivés alléniques du plomb, de l'étain et du mercure permettent d'observer les satellites dûs aux couplages métal‐proton à travers deux et quatre liaisons. L'analyse de ces satellites montre que 2J(XH) et 4J(XH) sont de signes contraires pour X = 207Pb, 119Sn, 117Sn et de même signe pour X = 199Hg.Les signes absolus probables des constantes de couplage réduites sont discutés en fonction des résultats de la littérature: 2K(XCH) est très probablement positif pour X = 207Pb, 119Sn, 117Sn et 199Hg.4K(XCCCH) est probablement négatif pour X = 207Pb, 119Sn, 117Sn, et positif pour X = 199Hg.
Stereochemical characterization of some mono‐ and diaryl substituted ethylene oxides by NMR spectroscopy
Authors: Ceccarelli Giulio , Berti Giancarlo , Lippi Giorgio , Macchia Bruno 
Published: May 2005

AbstractNMR spectra of several styrene, stilbene and stilbazole oxides have been determined, and chemical shifts and coupling constants have been correlated with cis‐and trans‐configurations. Assignments have been made for all protons, and double resonance technique and 13CH coupling constants have been used in some particular cases. An explanation is proposed for the observation that chemical shifts of oxirane protons are higher for cis than for trans isomers.
High resolution proton magnetic resonance spectra of heterocyclics 1,4‐benzodithiin and 1,4‐benzodioxin
Authors: Deb K. K. , Bloor J. E. , Cole T. C. 
Published: May 2005

AbstractThe proton magnetic resonance spectra of 1,4‐benzodithiin and 1,4‐benzodioxin have been fully analyzed. The effects of the substituent heteroatoms on the chemical shifts of the various protons in the two molecules have been discussed.
Protonenresonanz‐Untersuchungen an Polysaccharid‐Derivaten—II: CELLULOSEDERIVATE
Authors: Friebolin H. , Keilich G. , Siefert E. 
Published: May 2005

AbstractAm Beispiel der Cellulosederivate wurde gezeigt, wie es mit Hilfe der PR‐Spektroskopie—speziell bei einer Meßfrequenz von 220 MHz—möglich ist, in Polysacchariden zwischen einer Hexose und Pentose zu unterscheiden, die Konfiguration und die Konformation des Monomerbausteins im Polymeren sowie die Art der glycosidischen Bindung zu bestimmen. Voraussetzung für diese Untersuchungen sind die Acetyl‐, Benzoyl‐ oder Methylderivate des Polysaccharids, wobei der Polymerisationsgrad bei den Acetaten und den Methyläthern Pw < 200, bei den Benzoaten sogar Pw < 100 sein sollte.
Further evidence of the intrinsic chemical shift non‐equivalence
Authors: Dąbrowski Janusz , Ejchart Andrzej , Biernacki Władysław 
Published: May 2005

AbstractThe influence of hydrogen bonds on the chemical shift non‐equivalence of geminal methyl groups in recently investigated carbinols has been eliminated by using the formyl derivatives of the general formula RCH(OCHO)C(NO2)Me2. The observed increasing non‐equivalence, with the rise of temperature, provides more convincing evidence of the intrinsic non‐equivalence.
Carbon‐13 chemical shifts of bicyclic compounds
Authors: Lippmaa E. , Pehk T. , Paasivirta J. , Belikova N. , Platé A. 
Published: May 2005

Abstract13C NMR absorption spectra of 50 bicyclic hydrocarbons, alcohols and ketones have been measured, in addition to some terpenes. The 13C chemical shifts are approximately additive for similar compounds and can be used for the determination of molecular structure; they differ for endo‐ and exo‐isomers, just as in proton spectra. These quite regular and predictable 13C shift differences are much larger and are caused by the 1,4‐nonbonded interaction between atoms heavier than hydrogen, not by magnetic anisotropy effects.
Kernresonanzspektroskopische Untersuchungen an 3‐aza‐bicyclo[3.1.0]hexanen
Authors: Wendisch Detlef , Naegele Walter 
Published: May 2005

AbstractEs werden die kernresonanzspektroskopischen Parameter von drei 3‐Aza‐bicyclo[3.1.0]hexanen mitgeteilt, die aus den 100‐ und 220 MHz‐ Spektren durch Teilanalyse bzw. Durch iterative Computerberechnungen ermittelt wurden. Eine kurze Diskussion der erhaltenen Parameter in Hinblick auf die Struktur des 3‐Aza‐bicyclo[3 1.0]hexan‐Systems schließt sich an.
NMR spectra of Δ3‐ and Δ4‐pyrrolin‐2‐one
Authors: Mondelli R. , Bocchi V. , Gardini G. P. , Chierici L. 
Published: May 2005

AbstractThe spectra of Δ3‐ and Δ4‐pyrrolin‐2‐one were analysed and the sign of all the coupling constants determined by tickling and triple resonance experiments. A positive allylic interaction (Jxz in 2) is reported and four‐bond couplings are discussed in particular. Deuterium exchange affords evidence for the tautomeric equilibrium between 1 and 2.
Isomérie Polyédrique dans des Spirophosphoranes Possédant le Groupement PH
Authors: Houalla D. , Sanchez M. , Beslier L. , Wolf R. 
Published: May 2005

AbstractNous avons étudié la variation, en fonction de la température, des spectres de RMN de six spirophosphoranes des types: magnified imageLes résultats expérimentaux indiquent l'existence d'une isomérie intramoléculaire que nous avons interprétée en adoptant le mécanisme de pseudo‐rotation proposé par Berry.1Dans tous les cas, sauf un, le déplacement de l'équilibre tautomère spirophosphorane ⇌ phosphite s'ajoute an phénomène d'isomérie observé.
Heterocycles Contenant du Phosphore—V. Analyse des Spectres de Resonance Magnetique Protonique des Oxo‐2 Methoxy ou Phénoxy‐2, Methyl‐3, Oxazaphospholanes‐1,3,2: Exemples de Spectres du type ABXY
Authors: Devillers Jean , Navech Jacques , Albrand Jean‐Pierre 
Published: May 2005

AbstractLes 2 oxazaphospholanes étudiés ici donnent des spectres de RMP qui, après découplage du phosphore, peuvent ětre analysés comme des ABXY. Sur les huit solutions possibles, six peuvent ětre aisément éliminées et deux expériences de ‘tickling’ permettent de choisir entre les deux restantes. L'accord entre les spectres calculés, avec le programme LAOCOON III, et les spectres expérimentaux est très bon. La doubel résonance hétéronucléaire, les expériences de ‘tickling’ ou d'‘Indor’ permettent de déterminer les signes relatifs des constantes de couplages 3J(POCH) et 3J(PNCH). On vérifie également par l'expérience qu'aux signes négatifs de 2J HH correspondent des signes positifs pour les 3J HH. Quant à la conformation du cycle, si on ne peut l'établir avec certitude, on peut cependant constater, par comparaison avec les dioxaphospholanes, que l'introduction d'un groupement NCH3 ne semble pas introduire de dissymétrie et que le couplage 3J(PNCH) semble avoir une dépendance stéréochimique comparable à 3J(POCH).
The NMR‐spectrum of benzaldehyde partially oriented in the nematic phase
Authors: Diehl P. , Henrichs P. M. , Niederberger W. 
Published: May 2005

AbstractThe NMR spectrum of benzaldehyde oriented in the nematic phase of a mixture of p‐(p‐ethoxyphenylazo)phenylheptanoate and p‐(p‐ethoxyphenylazo)phenylundecylenate is analysed. It is demonstrated that the data are inconsistent with models in which the aldehyde group freely rotates or has minimum energy when it is perpendicular to the ring plane. The barrier height to rotation, however, cannot be obtained, nor is it possible to discriminate between the two possible solutions in which the averaging planar forms do or do not reorient in the liquid crystal between successive internal rotations.
Solvent effects in NMR spectra induced by benzene in aromatic N‐alkyl nitrones and O‐alkyl oximes—III
Authors: Alexandrou N. E. , Varvoglis A. G. 
Published: May 2005

AbstractNMR solvent effects induced by benzene on several N‐ and O‐alkyl oximes are reported. Both shielding and deshielding effects are observed and are accounted for by the geometry of the solute‐solvent ‘complex’. Good Hammett plots of solvent shifts for various types of protons are obtained.
Etude Conformationnelle d'Aldehydes a‐Thiopheniques et Furanniques par RMN
Authors: Roques B. , Fournie‐Zaluski M. C. 
Published: May 2005

AbstractNous avons effectué l'étude par RMN d'aldéhydes α‐thiophéniques et furanniques substitués et déterminé leurs conformations préférentielles par examen des valeurs des couplages stéréo‐spécifiques. On observe des modifications de la conformation du groupement aldéhydique en fonction de la nature des substituants placés en ortho. La conformation préférentielle de ces aldéhydes hétérocycliques est interprétée en fonction de l'existence de trois termes d'interactions.
Nuclear magnetic resonance spectra of carbanions—III: Tetraphenylethylene dianion
Authors: Takahashi Kensuke , Inoue Yoshio , Asami Ryuzo 
Published: May 2005

AbstractThe PMR spectra of the titled carbanion have been observed well‐resolved and suitable for first‐order analysis. Excess charges localized in the phenyl rings are estimated from the chemical shifts and compared with those observed in other carbanions.
Acetate‐methyl signals in the nuclear magnetic resonance spectra of peracetylated derivatives of some oligo‐ and polysaccharides
Authors: Hirano Shigehiro 
Published: May 2005

AbstractPeracetyl derivatives of oligo‐ and polysaccharides showed their own characteristic acetate‐methyl signals in the NMR spectra measured in chloroform‐d, which are useful for the identification and conformational analysis of oligo‐ and polysaccharides in solutions. An acetate‐methyl signal in the lowest field among three acetate‐methyl signals appeared in the NMR spectra of amylose acetate and was assigned to the acetate‐methyl signal at C6 on the basis of acetate‐methyl signals of peracetylated derivatives of 6‐O‐tosylamylose and xylan. Monosaccharide moieties in oligo‐ and polysaccharides examined were found in the C1 (D) conformation.
Distortion analysis of severely flattened rings
Authors: Lambert Joseph B. , Koeng Fred R. 
Published: May 2005

AbstractThe NMR spectra of the nonaromatic protons in several benzo‐substituted five‐ and six‐membered rings have been analyzed at 60‐ and 90‐MHz. The vicinal coupling constants from theCH2CH2fragments give a quantitative assessment of the degree of ring flattening. The distortions are discussed in terms of the structural components of the molecules.