bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR assignments and absolute stereochemistry of two guaianolide sesquiterpenes from Tanacetum densume subsp. amani
Authors: Ulubelen Ayhan , Gören Nezhun , Jiang Tian‐Yi , Scott Lincoln , Tianasoa‐Ramomojy Manoelson , Snyder John M. K.
Published: May 2005

The guaianolide sesquiterpene pyrethroidinin (1) and the corresponding ketone parishin A (2) wee isolated from Tanacetum densum subsp. amani (Asteraceae). The absolute stereochemistry of 1 was established as (1R, 3R, 6S, 7S, 10R) on the basis of the differential shielfing in the 1H NMR spectra of the (−)‐ and (+)‐O‐methylmandelate esters. The structure, including absolute stereochemistry, of 2 was confirmed by oxidation of 1 whit Jones' reagent.
Complete assignments of the 1H and 13C NMR spectra of some fluoro‐substituted chromenes
Authors: Barberis Claude , Campredon Myléne , Lokshin Vladimir , Giusti Gérard , Faure Robert
Published: May 2005

The total assignment of the 1H and 13C NMR spectra of four fluoro‐substituted chromenes was deduced from the concerted application of homonuclear correlation (COSY), 1H‐detected one‐bond heteronuclear multiple quantum coherence (HMQC) and long‐range (two and three bonds) heteronuclear multiple bond connectivity (HMBC) experiments.
Struktur‐Reaktivitätsuntersuchungen mit heterosubstituierten Nitrilen—VII:13C‐, 14N‐ und 19F‐NMR‐Spektroskopische Untersuchungen an Verbindungen vom Typ ArXCN
Authors: Radeglia R. , Storek W. , Engelhardt G. , Ritschl F. , Lippmaa E. , Pehk T. , Mägi M. , Martin D.
Published: May 2005

An aromatischen Nitrilverbindungen der allgemeinen Struktur para‐YC6H4XCN mit X = O, S, Se und N(CH3) wurden die 13C‐NMR‐ sowie für X = O die 14N‐NMR‐und für Y = F die 19F‐NMR‐chemischen Verschiebungen bestimmt. Die Meßergebnisse wurden in Zusammenhang mit der elektronischen Struktur der Moleküle (Substituentenkonstanten, π‐Elektronendichten in PPP‐Näherung) diskutiert.
Chemical polarisation of 15N and 13C nuclei in diazo coupling reactions
Authors: Lippmaa E. , Pehk T. , Saluvere T. , Mägi M.
Published: May 2005

Chemical polarisation of nitrogen and carbon nuclei in the decomposition and diazo coupling reactions of benzenediazonium fluoborate has been investigated. If homo‐ and heterolytic processes run in parallel in a multistage reaction sequence, then the nuclear polarisation created in a free‐radical reaction can be nearly quantitatively carried over to products of rapid ionic reactions such as azo dyes.
CIDNP as the proof of a radical mechanism of the reactions of Grignard reagents with diazonium salts
Authors: Savin V. I. , Temyachev I. D. , Kitaev Yu. P.
Published: May 2005

The PMR spectrum recorded during the reaction of tert‐butylmagnesium chloride with p‐chlorophenyl diazonium tetrafluoborate shows the CIDNP effect in the spectra of the the reaction products. Enhanced absorption and emission (the multiplet effect) has been observed for the protons of the vinyl group of isobutylene and the methyl protons of isobutane. The reaction of these diazonium salts with benzylmagnesium chloride results in only one polarised product, chlorobenzene. Such a polarisation proves the radical mechanism of the reaction which started with one‐electron transfer from the Grignard reagent to the diazonium salt.
Configurational assignments in some dihydrobenzo[c]thiophenes by NMR solvent effects. Correlation of the relative chemical shifts of α‐methyl groups with sulphoxide stereochemistry
Authors: Sataty Ishai
Published: May 2005

The configuration of isomeric 3,3‐dimethyl‐1‐phenyl‐1,3‐dihydrobenzo[c]thiophene 2‐oxides was assigned on the basis of selective benzene‐ and TFA‐induced NMR shifts. The same method was employed for assigning the α‐methyl resonances of these sulphoxides. Examination of NMR data for a variety of cyclic sulphoxides revealed that in CCl4 or CDCl3 solution, α‐hydrogen cis to SO often resonates at higher magnetic field, while α‐methyl group cis to SO characteristically resonates at lower field, than the same hydrogen or methyl group trans to SO, respectively.
Résonance Magnétique Nucléaire en phase nématique. Exploration de la barrière d'empêchement à la libre rotation de la monofluoroacétone
Authors: Courtieu J. , Gounelle Y.
Published: May 2005

Les spectres RMN des monochloro‐, monobromo‐ et monofluoroacétone orientées dans une phase nématique ont été interprétés et les constantes de couplage dipolaire mesurées. La barrière s'opposant à la libre rotation du groupement CH2F a été étudiée pour le composé fluoré à l'aide de différentes hypothèses. En utilisant une répartition de Boltzmann pour peupler les différentes conformations du groupement CH2F, et une fonction potentielle de la forme V(θ) = Σn Vn(1 – cos n θ)/2, on obtient un bon accord avec les résultats d'infra‐rouge pour V1 = 250 ± 50 cal.mol−1, V2 = 1650 ± 100 cal.mol−1, V3 = −1000 ± 100 cal.mol−1.
Carbon‐13 magnetic resonance spectra of quaternary ammonium salts derived from enamino ketones
Authors: Dabrowski Janusz , Kamieńska‐Trela Krystyna , Kozerski Lech
Published: May 2005

13C magnetic resonance spectra of nine quaternary ammonium salts of the general formula R1C1(O)C2HC3HNR34Cl (where R1, R4 = alkyl) were obtained and compared with those of the parent amino compounds. The chemical shift differences between these two classes of compounds are qualitatively accounted for by π‐electron density changes. Steric effects and hyperconjugation of the alkyl substituents are also discussed.
Chemical shift nonequivalence of sulfinates: Structural, solvent and temperature effects
Authors: Norton Richard V. , Douglass Irwin B.
Published: May 2005

The structural, solvent and temperature effects on the PMR spectra of several alkyl alkanesulfinates and arenesulfinates are discussed. A low order intrinsic nonequivalence was observed in substituents alpha to the sulfinate sulfur atom, the nonequivalence being significantly less than in sulfoxides, and solvent and temperature dependent. Nonequivalence of diastereotopic substituents on the ester oxygen exceeded nonequivalence in similar sulfoxides and is largely insensitive to temperatures from 25° to 120°C. Benzene complexes with sulfinates greatly enhancing the proton nonequivalence of alpha substituents apparently by causing a further shielding of the already more shielded nonequivalent protons.
Application of the temperature dependence of vicinal spin‐spin coupling constants to the investigation of the configuration of substituents in saturated 5‐membered rings
Authors: Filippova T. M. , Lavrukhin B. D. , Shmyrev I. K.
Published: May 2005

Temperature dependence of cis‐ and trans‐vicinal spin‐spin coupling constants of substituted cyclic 5‐membered compounds is discussed. The temperature dependence of trans‐vicinal coupling constants is shown to be essentially stronger than that of cis‐vicinal coupling constants if the energies of the conformers corresponding to potential energy curve minima are different. The temperature dependence of 33 vicinal spin‐spin coupling constants has been studied for di‐ and trisubstituted thiophanes with a known configuration of substituents. Experimentally determined changes of trans‐vicinal coupling constants with temperature are markedly larger than those for cis‐vicinal coupling constants, whose values, in most cases, are practically temperature independent. Differences in the temperature dependence of cis and trans‐vicinal spin‐spin coupling constants can be applied for the determination of the configuration of substituents in saturated 5‐membered rings.
13C chemical shifts of monosubstituted adamantanes
Authors: Maciel Gary E. , Dorn Harry C. , Greene Robert L. , Kleschick William A. , Peterson Max R. , Wahl George H.
Published: May 2005

13C chemical shifts are reported for adamantane, nine 1‐substituted adamantanes and nine 2‐substituted adamantanes. The substituents are F, Cl, Br, I, NH2, OH, CH2, CN and CO2H. The assignments and results are discussed in terms of chemical shift patterns.
The NMR spectra and conformations of cyclic compounds: IX—conformational studies of bicyclo(3,1,0)hexane derivatives by 13C NMR
Authors: Abraham Raymond J. , Holden Collette M. , Loftus Philip , Whittaker David
Published: May 2005

The 13C spectra of α‐thujene (1), isothujone (2), (−)isothujol (3), (+)neoisothujol (4), sabinol (5), dihydroumbellulone (6) and umbellulone (7) and the alcohol acetates are recorded and assigned. The C‐6 chemical shift may be used in conjunction with the steric shift mechanism as a conformational probe in these molecules. The results obtained indicate that isothujol, neoisothujol, isothujone and dihydroumbellulone adopt boat‐like conformations whilst sabinol has a much flatter conformation. Conjugation of the isolated double bond of α‐thujene and the carbonyl group of dihydroumbellulone with the cyclopropane ring has virtually no effect on the 13C shifts, but those of umbellulone itself are anomalous, indicating conjugation of the α,β unsaturated ketone system with the cyclopropyl ring.
The 1H NMR spectra of p‐substituted phenyl 2‐chloro‐2‐fluoroethyl sulphides
Authors: Takahashi Kensuke , Akasaka Takeshi , Kondo Shuji , Tsuda Kazuichi
Published: May 2005

The 60 MHz 1H NMR spectra of p‐substituted phenyl 2‐chloro‐2‐fluoroethyl sulphides have shown characteristic patterns; in the ABC portion of an ABCX spin system (X = 19F) of the compounds, one of the subspectra shows an ABC pattern and the other apparently an AB2 pattern. These spectral patterns have been analysed and the 1H NMR data obtained are discussed briefly.
Hétérocycles contenant du phosphore. XXII—Etude par RMP de dérivés de l'oxazaphospholane‐1,3,2: II—Analyse des spectres de composés monosubstitués en 5 ou disubstitués en 4 et 5.
Authors: Devillers Jean , Cornus Martine , Roussel Jean , Navech Jacques , Burgada Ramon
Published: May 2005

L'influence de différents facteurs (température, nature et concentration du solvant) ou l'utilisation de différentes techniques de double irradiation (par exemple, tickling ou INDOR) est mise à profit pour analyser le spectre de RMP de toute une série de dérivés de l'oxazaphospholane‐1,3,2 possédant soit un substituant sur le carbone en 5, soit deux substituants sur les carbones en 4 et 5.
Etude du couplage 2J(N15H) en série hétérocyclique. Application à la détermination des constantes d'équilibres prototropiques rapides
Authors: Maquestiau A. , Van Haverbeke Y. , Muller R. N.
Published: May 2005

La comparasion des constantes de couplage 2J(N15H3) présentées par la (N15)‐4‐phénylisoxazoline‐5‐one (2) et par deux de ses formes fixes, la (N15)‐2‐méthyl‐4‐phénylisoxazoline‐5‐one (3) et le (N15)‐4‐phényl‐5‐méthoxyisoxazole (4), indique une participation élevée de structure énolique (et/ou ionique) dans les milieux basiques.
NMR spectroscopic study of rotation around CC and CN bonds in diene δ‐aminocarbonyl compounds
Authors: Prokof'ev E. P. , Krasnaya Zh. A. , Kucherov V. F.
Published: May 2005

A relatively fast rotation around the α,β carbon–carbon double bond at the equilibrium of geometrical isomers and a comparatively slow rotation around the carbon‐nitrogen single bond in compounds of the type

(X1, X2 are electron‐attracting substituents) were detected and investigated by the NMR technique. The relationships between the free energies of activation for these rotational processes and the character of the substituents, the number of double bonds, solvents and concentration were studied.
The NMR spectra of the carbanions of xanthene and thioxanthene. Evidence for paratropism
Authors: Vos H. W. , Bakker Y. W. , MacLean C. , Velthorst N. H.
Published: May 2005

The proton NMR spectra of the carbanions of xanthene [XH]− and thioxanthene [TxH]− have been recorded and interpreted. Paratropism in the central rings of [XH]− and [TxH]− is inferred from a comparison of the chemical shifts with those of the carbanion of 9,10‐dihydroanthracene [AH]−. The contributions to the chemical shifts arising from n‐electron excess charges, local dipoles and magnetic anisotropies are discussed. Numerical values for the various ring currents have been estimated by a least squares analysis of the observed chemical shifts after applying corrections for the excess charge effect. The results point to a strongly increasing paramagnetic ring current in the central ring in the order [AH]−, [TxH]−, [XH]−.
Studies of 13CH coupling constants: III—the conformational dependence of 1J(13CH) for the formyl proton in aromatic aldehydes
Authors: Ewing D. F.
Published: May 2005

1J(13CH) and 2J(13CH) involving the aldehydic proton in ortho‐alkylbenzaldehydes have been examined for evidence of a hyperconjugative contribution from the aromatic π‐electrons. The expected hyperconjugative effect is obscured by changes in the coupling constants resulting from steric inhibition of resonance.
NMR experiments on acetals. 300 MHz spectrum and conformational aspects of the 1‐aza‐4,6‐dioxabicyclo[3.3.0]octane system
Authors: Anteunis Marc , Gelan J. , Van Cauwenberghe R.
Published: May 2005

Complete analyses of the 300 MHz 1H NMR spectra of 1‐aza‐4,6‐dioxabicyclo[3.3.0]octane (1a), the 5‐Me‐ (1b), and both the cis‐ and trans‐3,5‐diMe‐ derivatives (1c and 1t), as well as most of the corresponding methiodides are reported. Spectral data suggest probable conformations to be 11 (1a, 1b and 1c) and 13 (1t), respectively. The corresponding methiodides adopt slightly different forms, having flattened NC‐2C‐3 moieties (12 for 2a, 2b and 2c).
A study of 5‐membered ring conformations by the temperature dependence of the vicinal spin–spin coupling constants. Conformations of cis‐ and trans‐isomers of 4‐benzoylamino‐3‐acetoxythiophane
Authors: Lavrukhin B. D. , Filippova T. M. , Fedin E. I.
Published: May 2005

Conformational equilibrium in cis‐ and trans‐4‐benzoylamino‐3‐acetoxythiophanes has been analysed on the basis of the temperature dependence of the vicinal spin–spin coupling constants. The conformations of the compounds have been established. It has been shown that in problems of this kind the real accuracy of the experiments corresponds to a wide range of spin‐spin coupling constant values and differences between the conformer energies. To narrow the range, additional data have been used, such as the temperature dependence of other vicinal coupling constants in the same molecule, angular dependence of the vicinal constants, etc.
Long range carbon—carbon coupling in olefins. 4‐13C‐4‐propyl‐3‐heptene and 1‐13C‐1‐methylcyclohexene
Authors: Marshall James L. , Miller Denis E.
Published: May 2005

All 13C—13C splittings involving the C‐4 carbon of 4‐propyl‐3‐heptene and the C‐1 carbon of 1‐methylcyclohexene were determined from the appropriately labeled (> 90%‐13C) derivatives. The observed trends in coupling constants continue to offer additional means of carbon chemical shift assignments and to provide mechanistic information regarding the nature of long range carbon—carbon coupling.
Carbon‐13 nuclear magnetic resonance spectroscopy IX—monosubstituted ethylenes
Authors: Miyajima Goh , Takahashi Kensuke , Nishimoto Kichisuke
Published: May 2005

Carbon‐13 chemical shifts of sixteen monosubstituted ethylenes were obtained. In order to explain the chemical shifts, σ and π electron densities of these compounds are calculated by the σ‐included ω‐HMO method.

See Ref. 8.

A linear relationship exists between carbon‐13 chemical shifts and the calculated electron densities, and also between substituent constants and electron densities. A slope of unity is obtained between the chemical shifts of α carbons of monosubstituted ethylenes and those of carbons adjacent to the substituents in monosubstituted benzenes. On the other hand, a plot of chemical shifts of Cortho of benzene derivatives against that of the β carbon in ethylene derivatives gives a slope of 3. These slopes can be explained by the calculated electron densities. A slope of 4/3 is obtained between the direct coupling constant 1J(CH) of the α carbon in monosubstituted ethylenes and that in the corresponding substituted methanes.
Das 13C‐NMR‐Spektrum von β‐Carotin und die Ladungsverteilung in der Polyenkette von Apocarotinalen
Authors: Bremser W. , Paust J.
Published: May 2005

Eine Zuordnung der 13‐Resonanzfrequenzen von β‐Carotin gelingt als Grenzwert einer Serie von Apocarotinalen mit wachsender Kettenlänge. Dadurch erhält man genauen Einblick in die abklingende Polarisierung der Doppelbindungen mit wachsendem Abstand von der Carbonylgruppe und mit Hilfe der Relaxationszeiten in die Beweglichkeit des Moleküls.
Conformational analysis of the tropane analogue of pethidine and related compounds by 1H NMR spectroscopy
Authors: Casy A. F. , Coates J. E.
Published: May 2005

The 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‐diphenylhydroxymethyl‐3β‐tropanol and 3α‐phenyl‐3β‐tropanyl phenyl ketone. In the hot‐plate test for analgesia performed on mice, ethyl 3α‐phenyltropane‐3β‐carboxylate is about 1·5 times as effective as pethidine.
Assignment of carbon‐13 NMR spectra and sign determination of long range carbon‐13—proton coupling constants with SPI
Authors: Chalmers A. A. , Pachler K. G. R. , Wessels P. L.
Published: May 2005

The application of selective population inversion (SPI) to the assignment of 13C resonances and to the determination of the relative sign of 13C1H coupling constants is demonstrated for 1‐phenyl‐1,2‐dibromo‐2‐nitroethane. A negative sign for the geminal C‐2H‐1 coupling constant has been determined from the 13C spectra. The relationship between SPI and TSI is discussed.
Carbon‐13 NMR spectra of retinal1 and its related compounds
Authors: Inoue Yoshio , Takahashi Akio , Tokitô Yasuo , Chûjô Riichirô , Miyoshi Yasuhiro
Published: May 2005

Carbon‐13 NMR spectra of all‐trans retinal1 and vitamin A1 were measured by the pulse Fourier transform method in CCl4. All peaks in these spectra were assigned from considerations of chemical shifts, half proton‐decoupled spectra, spin‐lattice relaxation times and induced chemical shift by the addition of shift reagent. The carbon‐13 NMR spectrum was also measured for all‐trans retinal1 which had been exposed to the sunlight for three hours, and the induced isomer was proposed to be 11‐s‐cis retinal1.
Substituent effects on long range proton–proton couplings in 4‐substituted bornanones
Authors: Morris D. G. , Murray A. M.
Published: May 2005

Long range proton–proton coupling constants between H3exo and H5exo have been measured in a series of 4‐substituted bornanones. Correlation between the magnitudes of 4J3exo–5exo and the inductive linear free energy σI has been obtained. 4‐Substituted bornanone nitrimines exhibit diminished values of 4J3exo–5exo with respect to the parent ketone.
Solvent effects on the NMR spectra of heterocyclics
Authors: Rao G. Venkoba , Balakrishnan M. , Subramanian N. Venkata
Published: May 2005

The NMR spectra of pyridine, pyrazine and imidazole are examined in acetone‐d6. The differential shifts of the ring protons are accounted for in terms of an interaction between the lone pair on the ring nitrogen atom and the carbonyl group of acetone.
Epoxydes cyclopentaniques conformationnellement homogènes. II—Détermination des configurations au moyen des déplacements chimiques induits par compléxation a l'Europium
Authors: Vidal Jean‐Pierre , Girard Jean‐Pierre , Rossi Jean‐Claude , Chapat Jean‐Pierre , Granger Robert
Published: May 2005

La configuration de divers époxydes conformationnellement homogènes en série bicyclo‐(n.3.0) alcanique trans est établie par compléxation progressive avec avec Eu(dpm)3. Les exemples décrits mettent en évidence l'importance de cette technique qui est très supérieure à tous les autres procédés physico‐chimiques déjà mis en oeuvre pour déterminer la configuration des époxydes en série cyclopentanique.
Détermination des configurations Z et E d'imines par RMP. Combinaison de l'étude directe et en présence d'Eu(fod)3
Authors: de Savignac Alain , Lattes Armand , Bon Mme Maryse
Published: May 2005

La combinaison de l'étude directe des spectres de RMN du proton et des déplacements induits par le complexe Eu(fod)3 a permis d'étudier les phénomènes d'isomérie syn‐anti (Z‐E) dans un certain nombre d'imines cycliques et acycliques. Un cas d'équilibration syn ⇌ anti par addition d'Eu(fod)3 a pu être mis en évidence.
Structure du propyne par RMN en phase nématique. Utilisation des satellites du carbone‐13
Authors: Haloui Ezzeddine , Canet Daniel
Published: May 2005

Le spectre protonique ainsi que les satellites du carbone‐13 du propyne orienté dans un solvant nématique permettent d'accéder à la structure complète de cette molécule. L'accord avec les résultats obtenus par spectroscopie micro‐onde est excellent.
Carbon‐13 NMR spectra of some tetra‐ and pentacyclic triterpenoids
Authors: Knight S. A.
Published: May 2005

The carbon‐13 NMR spectra of lanosta‐8‐en‐3β‐ol, lanosta‐8, 24‐dien‐3β‐ol, lanosta‐7,9(11)‐dien‐3β‐ol, lanostan‐3β‐ol, eupha‐8‐en‐3β‐ol, eupha‐8,24‐dien‐3β‐ol, ursa‐12‐en‐3β‐ol (α‐amyrin) and oleana‐12‐en‐3β‐ol (β‐amyrin) have been obtained and completely assigned. The results of this study provide chemical shift data for methyl, methylene, methine and quaternary carbon atoms in tetra‐ and pentacyclic triterpenoid spectra. The carbon‐13 NMR spectrum of a triterpenoid provides a unique fingerprint for the molecule.
Proton and 13C NMR spectra of substituted methyl cyanopropionates: Effects of molecular asymmetry
Authors: Schwarz Meyer , Bradley Robert B. , McIntyre H. Michael , Becker Edwin D.
Published: May 2005

The proton NMR spectra at 220 MHz of two series of substituted cyanopropionates,
magnified image
have been investigated. In addition the 13C spectra at 15 MHz of the series I were also studied. In I, where the R groups are diastereotopic, differences are observed in the proton chemical shifts of the CH3 groups in R for R = CH3, C2H5, n‐C3H7, i‐C3H7, n‐C4H9, n‐C5H11 and n‐C6H13. In II [R′ = n‐C3H7, CH(CH3)2, CH2CH(CH3)2 and C(CH3)3] diastereoisomers are found with substantial differences in chemical shifts between corresponding protons. Coupling constants are interpreted in terms of conformational preferences for certain molecules in both series.
Etude par Résonance Magnétique Nucléaire de dioxaphosphorinanes‐1,3,2 à liaison PN extracyclique. Exemple de changement d'orientation de la liaison PN
Authors: Cogne André , Guimaraes Afonso G. , Martin Jean , Nardin Robert , Robert Jean‐Bernard , Stec Wojciech J.
Published: May 2005

Le spectre de résonance magnétique nucléaire du proton de divers dioxaphosphorinanes‐1,3,2, qui portent au niveau du phosphore une liaison PN extracyclique a été analysé. Cette étude confirme que, pour une disposition géométrique donnée des atomes P, O, C et H, le couplage 3J(POCH) dépend fortement de l'orientation des liaisons au niveau du phosphore. Suivant la nature des restes attachés à l'atome d'azote, le cycle dioxaphosphorinane adopte une forme du type chaise rigide à liaison PN axiale ou équatoriale, ou au contraire une forme chaise qui s'inverse rapidement pour le temps d'observation de la RMN.
Etudes conformationnelles par Résonance Magnetique Nucléaire et variations de températures d'éthanes di‐ et trisubstitués
Authors: Rouvier Emile , Pastor Raphaël , Musso Jean , Cambon Aimé
Published: May 2005

Nous présentons dans ce travail l'étude conformationnelle de divers éthanes di‐ ou trisubstitués par des groupements N‐dialkyle, thioalkyl, alcoxy, N‐pyrrolidino, N‐benzyl, nitrile ou methoxycarbonyle. Les spectres ont été analysés par une méthode basée sur les déplacements chimiques. La stabilité relative des isomères de rotation est discutée en fonction des paramètres structuraux accessibles (géométriques et électroniques).
Carbon‐13 NMR spectra of monosubstituted pyrazines
Authors: Turner C. J. , Cheeseman G. W. H.
Published: May 2005

Carbon‐13 NMR chemical shifts and one‐bond carbon–hydrogen coupling constants have been obtained at 15·09 MHz. The trends in the carbon chemical shifts obtained for the pyrazines parallel those of monosubstituted benzenes and 2‐substituted pyridines, except for the direct effect of substitution where the pyrazines resemble pyridines not benzenes. The substituent effects on the 13C NMR spectra are generally quite similar to those in the 1H NMR spectra. The 13C NMR spectrum of the tautomeric hydroxypyrazine has been compared with the 13C NMR spectra of 2‐, 3‐ and 4‐hydroxypyridines. Hydroxy compounds that can exist as a cyclic amide show a large meta substituent effect on the chemical carbon shift.
NMR determination of the enantiomer composition of penicillamine using an optically active europium shift reagent
Authors: Cockerill Anthony F. , Davies Geoffrey L. O. , Harrison Roger G. , Rackham David M.
Published: May 2005

An NMR method is described for assaying the enantiomer composition of the pharmacologically active material penicillamine (1), using tris‐(3‐heptafluorobutyryl‐d‐camphorato)europium. The L enantiomer can be detected at levels of 0·4 to 0·5% in DL mixtures. Problems due to the insolubility of penicillamine in nonpolar solvents can be overcome by a two step derivatisation procedure.
Interactions intramoleculaires. XXI—Constantes de couplage et interactions gauches avec un groupement t‐butyle (molécules cyclohexaniques deutériées)
Authors: Aycard Jean‐Pierre , Bodot Hubert
Published: May 2005

Une ou plusieurs modifications isotopiques sont mises en évidence par l'analyse des spectres RMN des produits de deutériation du t‐butyl‐1 méthoxycarbonyl‐4 cyclohexène (d4‐3,3,6,6), des méthyl‐3 cyano‐4 cyclohexène (d3‐3,6,6) cis et trans, des t‐butyl‐3 méthoxycarbonyl‐4 cyclohexènes (d3‐3,6,6) cis et trans et des t‐butyl‐3 cyano‐4 cyclohexènes (d3‐3,6,6) cis et trans. D'après la comparaison des constantes de couplage 3J et 4 J des molécules modèles et des molécules à fortes interactions gauches, il est prouvé que ces dernières sont en conformation chaise avec des déformations de cycle relativement modérées.
Proximity effects in pyridines. Proton chemical shifts in substituted methyl pyridinecarboxylates
Authors: Deady L. W. , Harrison P. M. , Topsom R. D.
Published: May 2005

Ring and ester proton chemical shifts in six series of substituted methyl pyridinecarboxylates have been measured. Results for ring protons ortho and para to the substituent can generally be accounted for by additive substituent, ester and nitrogen effects. Shifts for protons meta to the substituent, when compared with analogous shifts in monosubstituted benzenes, provide evidence of substituent–nitrogen interactions. In particular, a special effect is noted for series where both the proton and substituent are adjacent to the nitrogen. The origin of this effect is discussed. The ester proton results lead to essentially the same conclusions. Although this probe is much less sensitive to substituent effects, the same special effect is evident for the methyl 6‐X‐picolinate series.
NMR spectral analysis of 1,3,2‐dithiaphosphorinanes and 1,3‐dithianes
Authors: Martin J. , Robert J. B.
Published: May 2005

The full set of NMR spectral parameters (1H, 13C, 31P) are reported for 2‐phenyl‐1,3,2‐dithiaphosphorinane and 2‐phenyl‐1,3‐dithiane. The stereochemical dependence of the coupling constants is discussed.
The solvent‐induced shift in the proton NMR of some quinolizidine substituents
Authors: Lalonde Robert T. , Donvito Thomas N. , Tsai Amy I‐M. , Wong Chunfook
Published: May 2005

The proton chemical shift values for the methyl groups in the nine monomethylquinolizidines are determined in deuterochloroform and benzene solutions. This solvent change results in the shielding of all the methyl groups except those in 1(a)‐and 3(a)‐methylquinolizidine which become deshielded. These results are compared with those obtained earlier for equatoral and axial methyl and methylene groups attached to the quinolizidine systems in Nuphar alkaloids and related compounds.
Hochauflösungs‐13C‐NMR‐Spektroskopie. I—Analyse der Spektren des 1,2,4‐ und 1,3,5‐Triazins sowie ihrer Methyl‐ und Phenylderivate
Authors: Braun S. , Frey G.
Published: May 2005

Mit Hilfe der Puls‐Fourier‐Transform‐Technik wurden die Hochauflösungs‐13C‐NMR‐Spektren des 1,2,4‐ und 1,3,5‐Triazins sowie ihrer Methylderivate aufgenommen, ferner auch die 1H‐breitbandentkoppelten 13C‐Spektren von phenyl‐ und methyl‐phenyl‐substituierten Triazinen. Die chemischen Verschiebungen der mehrfach substituierten 1,2,4‐Triazine verhalten sich weitgehend additiv; Abweichungen bei Phenylderivaten werden sterischen Ursachen zugeschrieben. Die 13CH‐Kopplungskonstanten werden mit denen im Benzol, im Pyridin, in den Diazinen sowie in disubstituierten Äthylenen verglichen. Der starke Einfluß von Anzahl und Position der Stickstoffatome auf die Kopplungskonstanten läßt sich daran erkennen, daß im 1,2,4‐Triazin, entgegen der üblichen Reihenfolge, geminale Kopplungen größer als vicinale sind.
Interactions intramoleculaires: XXII—Constantes de couplage, équilibres conformationnels et interactions gauches avec un groupement t‐butyle (molécules cyclohexéniques deutériées)
Authors: Aycard Jean‐Pierre , Bodot Hubert
Published: May 2005

Les paramètres RMN d'une série de cyclohexènes disubstitués (R = CH3, (CH3)3C; X = COOCH3, CN) et spécifiquement deutériés sont déterminés. A partir des valeurs des constantes de couplage 3J(HH), 3J(HD), 4J(HH) et 5J(HH), les équilibres conformationnels sont évalués. Trois des cinq composés ayant un groupement t‐butyle en position allylique sont conformationnellement hétérogènes; les équilibres correspondants et les équilibres entre stéréoisomères permettent une analyse de ce phénomène dans le cadre de l'hypothèse de l'additivité des enthalpies libres conformationnelles et des interactions gauches.
Studies of the kinetics of the interaction between N‐trifluoroacetlyl‐D‐tryptophan and α‐chymotrypsin by pulsed nuclear magnetic resonance
Authors: Gerig J. T. , Stock A. D.
Published: May 2005

The Carr‐Purcell experiment first used by Allerhand and Gutowsky for the determination of chemical exchange rates has been applied to the study of an enzyme inhibitor complex. Chemical shift and relaxation time data obtained by analysis of pulsed fluorine NMR data collected at 51 MHz are shown to be consistent with high resolution results assembled at 94° 1 MHz. The rate constants for dissociation of the N‐trifluoroacetyl‐D‐tryptophan‐α‐chymotrypsin complex were determined to be 1 × 104 s−1 at 26°C and 2 × 103 s−1 at 6·5°C. The resonance position of the fluorine nuclei of the inhibitor is shifted downfield ∼1 ppm upon complexation to the enzyme, and the trifluoromethyl group suffers some restriction of molecular motion in the bound state as indicated by T1 and T2 data.
NMR study of catechol and some catecholamines
Authors: Lambert Françoise , Ellenberger Michel , Merlin Louis , Cohen Yves
Published: May 2005

The proton magnetic resonance spectra of catechol, epinephrine, dopamine, synephrine, tyramine and amphetamine have been analysed by computer simulation. The chemical shifts and coupling constants are discussed, with their molecular implications. Convenient parameters are introduced for the additivity of substituent effects on chemical shifts of aromatic protons. The additivity rule of coupling constants is extended to these compounds.
Alcoxyflurophosphoranes. II—Monoalcoxyfluorophosphoranes possédant un centre d'asymétrie; diastéréotopie des fluors apicaux
Authors: Robeert Dominique U. , Costa D. Jean , Riess Jean G.
Published: May 2005

Vingt‐six monoalcoxyfluorophosphoranes comportant un group asymétrique et appartenant aux types R1PF3(OR2*) (1), R1*PF3(OR2) (2), R1R3PF2(OR2*) (3) et R21PF2(OR2*) (4) ont été préparés. La non‐équivalence des fluors occupant les sites apicaux de la bipyramide trigonale est mise en évidence par RMN de 19F pour les types 1 (δFa) – δF′a ∼ 0,5 à 3,8 ppm. J(FaFa′) ∼ (10 Hz), 2 δFa – δF′a ∼ 1,1 à 1,5 ppm, J(FaFa)′ ∼ 14 Hz et 3 δFa ‐ δF′a ∼ 0,2 ppm J(FaFa′) ∼ 10 Hz, mais non pour les types 4 R12PF2(OR2*) Elle est attribuée à la diastéréotopie de ces fluors apicaux. La possibilité d'une gěne à la rotation des substituants est exclue. La synthèse de sec‐BuPF4 et EtPhPF est également décrite.
Etude par RMN du proton d'hétérocycles voisins de l'oxazaphospholane‐1,3,2. I—La phényl‐3 oxo‐2 oxathiazolidine‐1,3,2
Authors: Devillers Jean , Cornus Martine , Navech Jacques , Cazaux Louis
Published: May 2005

L'analyse complète du spectre de résonance du proton du composé du titre est mise à profit pour une étude conformationnelle de la molécule au niveau C‐4—C‐5. La position relative des protons vis à vis de la liaison S=O est fixée grâce à l'utilisation du complexe de l'Europium Eu(fod)3. Les résultats obtenus sont tout à fait cohérents avec ceux trouvés pour des composés similaires contenant, ou non, un atome de phosphore.
Constantes de couplage de vinylallènes
Authors: Lefèvre F. , Martin M. L. , Le Bail H. , Odiot S.
Published: May 2005

Afin de préciser l'influence d'une conjugaison de type allénique les spectres RMN du vinylallène et de plusieurs de ses dérivés méthylés ont été analysés et les signes des constantes de couplage ont été déterminés. Ces composés présentent une structure s‐trans plane des deux doubles liaisons non cumulées. Une discussion des paramètres et no amment de l'influence des substitutions méthylées fait ressortir une forte prédominance des contributions de type π. Cette interprétation est corroborée par les calculs théoriques des constantes de couplages, effectués par la méthode de perturbations finies CNDO et INDO.
NMR studies on benzaldehydes. III—Rotational isomerism and torsional barriers in stable protonated o‐ and m‐substituted benzaldehydes
Authors: Jost R. , Sommer J. M. , Drakenberg T.
Published: May 2005

Proton and carbon‐13 NMR spectroscopy have been used to obtain the torsional barrier in some protonated ortho and meta substituted benzaldehydes, and the relative populations of the O‐cis and O‐trans rotamers have been determined. The results are compared with earlier data on free benzaldehydes.
Three chlorinated bipyridine compounds: Quantum calculations and their relationship to the molecular structure and physicochemical properties of the molecules considered
Authors: Redshaw Mavis
Published: May 2005

The Cl35 nuclear quadrupole resonances were measured for three chlorinated bipyridine compounds. The number of resonances obtained is explained in terms of the position of one ring of the compound with respect to the other. Quantum chemical calculations

Details of the computer programs used are available from the author on request.

confirm the explanation given.
Carbon‐13 NMR spectra of some polychloro hydrocarbons and related compounds
Authors: Velichko F. K. , Chukovskaya E. C. , Dostovalova V. I. , Kuzmina N. A. , Freidlina R. Kh.
Published: May 2005

Data derived from the carbon‐13 NMR spectra of 37 organic polychloro compounds allow one to identify readily the CHCl2, CCl2 and CH2Cl groups, the 13C signals of which are registered in the shift ranges of 67 to 78 (80), 85 to 96 and 38 to 55 (59) ppm (from TMS), respectively, and have the distinctive one bond spin‐spin coupling constants 1J(CH) 170 to 184 Hz (for the CHCl2 groups) and 147 to 158 Hz (for the CH2Cl groups). The CCl2CH2CH2Cl fragment features characteristic diamagnetic shieldings of the CCl2 and CH2Cl that may be related to increased electron density on both of these groups.
Etudes configurationnelles et conformationnelles de quelques chlorures de désoxy‐6 β‐L‐héxopyrannosyle chlorosulfonyles et de leurs glycosides de méthyle
Authors: Hajdukovic G. , Martin M. L. , Sinaÿ P. , Pougny J. R.
Published: May 2005

Une analyse complète des spectres RMN de désoxy‐6 L‐hexopyrannoses de configuration α et des anomères β correspondants est réalisée. L'ensemble des paramètres obtenus confirme l'existence d'une structure chaise 1C (L) présentant une disposition axiale du substituant anomère dans le cas des α‐fuco‐, α‐rhamno‐ et α‐chinovopyrannosides de méthyle et des chlorures de α‐fuco‐ et α‐rhamnopyrannosyle. La structure reste de type chaise 1C (L) dans le cas des β‐fuco‐ et β‐chinovopyrannosides de méthyle. Il en est de même en dépit de I'effect anomère dû à I'atome de chlore, pour les chlorures de β‐fuco‐et β‐rhamnopyrannosyle. Par contre les paramètres RMN du chlorure de β‐chinovopyrannosyle ne semblent interprétables ni sur la base d'une géométrie chaise à chlore équatorial ni par une structure bateau.
Carbon‐13 NMR spectroscopy of hop bitter substances
Authors: Borremans F. , De Potter M. , De Keukeleire D.
Published: May 2005

The 13C NMR spectra of the most important hop bitter substances are analysed. All individual carbon atoms are assigned, except the oxygen bonded sp2 carbon atoms. Most assignments are made partly by comparison with analogous compounds and partly by reference to literature data. Cross‐correlations with the 1H NMR shifts are made for two main products and confirm the correctness of the assignments. All data are in agreement with the known structures.
Azolides. VII—Restricted rotation in N‐acylindoles and carbazoles. Anisotropy effect of the carbonyl group
Authors: Elguero José , Marzin Claude , Peek Michael E.
Published: May 2005

The barrier to internal rotation about the NC bond and the E/Z configuration of some N‐acetyl and N‐formylindole derivatives have been determined and discussed in terms of electronic and steric effects. The barriers to internal rotation have been determined for certain N‐acetylcarbazoles and some new N‐formyl derivatives of carbazole. Experimental proof is also given, showing that contrary to the provisions of the classical model of carbonyl anisotropy, the protons (α and peri positions) next to the oxygen of the acyl group are displaced to high frequencies. This result allows one to determine the preferred configuration of N‐acetyl derivatives of perimidine and 1H‐naphtho[1,8‐de]triazine.
Influence of chemical exchange on the temperature dependence of Eu(fod)3‐induced shifts
Authors: Samitov Yu. Yu. , Bikeev Sh. S.
Published: May 2005

Temperature dependences of the paramagnetic shifts induced by Eu(fod)3 in 1H NMR spectra of ethylene oxide in carbon disulphide solution are obtained in the temperature range from +40 to − 100°C at 100 MHz and from +30 to −60°C at 60 MHz. The influence of chemical exchange leads to a decrease of the observed paramagnetic shifts with decreasing temperature. It is shown that a modified Swift and Connick equation can be used to describe the observed dependences. Upper limits of the mean lifetimes of the Eu(fod)3‐ethylene oxide adduct are τp < 1·7 × 10−8 s at 14 °C and τp < 1 × 10−8 s at 20 °C, respectively. The corresponding activation energy is equal to Va = 13·7 kcal/mol.
1H‐NMR‐Spektroskopische Untersuchungen zur Konformation von Cyclohexandicarbonsäure‐(1,2)‐anhydriden
Authors: Werner H. , Zschunke A. , Mann G. , Kleinpeter E.
Published: May 2005

Die chemischen Verschiebungen der 1H‐NMR‐Spektren von 18 methylsubstituierten Cyclohexandicarbonsäure‐(1,2)‐anhydriden wurden bestimmt. Von den unsymmetrisch sub‐stituierten Verbindungen wurden die vicinalen Kopplungskonstanten ermittelt. Bei den trans‐Anhydriden lässtsich aus den NMR‐Daten ableiten, dass der Sechsring in einer sesselähnlichen Form vorliegt. Auch bei den cis‐Anhydriden sind in den meisten Fällen Konformationen mit verdrillter Sesselanordnung des Cyclohexans bevorzugt.
The 250 MHz 1H NMR spectrum of cinnoline
Authors: Pappalardo Giuseppe C. , Gruttadauria Salvatore , Le Bail Henri
Published: May 2005

The proton NMR spectrum of cinnoline has been measured at high field (250 MHz) and analysed as an H‐8‐de‐coupled ABCXY and H‐4‐decoupled ABCX system. Inter‐ring HH couplings have been determined and discussed in relation to theoretical values obtained using INDO calculations.
Synthesis and structure assignments of cis‐ and trans‐2‐(diethylaminomethyl)cyclohexanols
Authors: Puar Mohindar S. , Cohen Allen I. , Krapcho John
Published: May 2005

The synthesis of cis‐ and trans‐2‐(diethylaminomethyl)‐cyclohexanols and their structural assignments by NMR using the shift reagent Eu(dpm)3 are described. The correlation of the induced shifts with the equation Δν = K(3 cos2θ – 1)r−3, assuming an EuO distance of 2·4 Å and θ less than 30°, suggests that the interactions are pseudocontact. The values of K are 452 and 420 for the two cyclohexanols, respectively.
On the mechanism of reaction of tert‐butoxyl radicals with dialkylphosphites
Authors: Brunton G. , Ingold K. U.
Published: May 2005

It has been shown by ESR spectroscopy that the title reaction involves abstraction of hydrogen from the phosphite, since at −10°C the reaction has a kinetic deuterium isotope effect, kH/kD, or ∼3. The rate constant for hydrogen abstraction is c. 2 × 104 M−1 s−1. There is no significant addition of alkoxyl radicals to the phosphite.
19F NMR analysis of the fluorides of perfluorocyclohexane‐sulphonic acid and of 3‐trifluoromethylperfluorocyclopentane‐1‐sulphonic acid
Authors: Gurato Giorgio , Cavalli Luciano , Troilo G. Giorgio
Published: May 2005

From the electrochemical fluorination of the chloride and the fluoride of benzenesulphonic acid, in addition to the main product C6F11SO2F, the side products C5F8(CF3)SO2F, a structural isomer of the main product and C6F10ClSO2F are also obtained.

The NMR analysis of these products was performed. Chemical shift and coupling constant values were obtained for all the compounds. The NMR parameters of the main product are compared with those of perfluoromethylcyclohexane according to the data of Jolley, Sutcliffe and Walker. From the NMR parameters of C5F8(CF3)SO2F it was possible to demonstrate that substitution on the ring for —SO2F and CF3— is of the 1,3 and not the 1,2 type.
Conformationally dependent influence of 3‐substituents on the observable magnetic non‐equivalence of benzylic methylene protons in N‐benzylpiperidines
Authors: Iorio M. A. , Casy A. F.
Published: May 2005

Examples are given of the conformationally dependent influence of 3‐substituents (methyl, n‐propyl, allyl, aryl, hydroxy and acyloxy) on the magnetic non‐equivalence of the benzylic methylene protons (NCH2Ph) of N‐benzylpiperidine as observable by 1H NMR. The results, together with data already reported, emphasise the value of 1H NMR studies of N‐benzyl derivatives in stereochemical investigations of substituted piperidines.
Additive NMR shielding parameters for some substituted cyclohexanols
Authors: Ceccarelli G. , Macchia B. , Macchia F. , Monti L.
Published: May 2005

The shielding effects of some substituents on the chemical shifts of the methine proton of axial and equatorial cyclohexanols have been calculated and rationalised. The remarkable downfield shift observed for the phenyl substituent has been discussed on the basis of Johnson‐Bovey and Haigh‐Mallion theories. The chemical shift of methine protons of some cyclohexanols have been calculated using additive shielding increments. Agreement between calculated and experimental values substantiates the use of the additivity principle in cyclohexyl systems and justifies the origin of certain marked inversions of the accepted rule that the axial protons resonate at lower fields than the corresponding equatorial ones.
NMR studies of the configuration of the isomeric 2,3‐dimethyloxetanes
Authors: Ewing D. F. , Holbrook K. A. , Scott R. A.
Published: May 2005

The 1H and 13C NMR spectra of cis‐ and trans‐2,3‐dimethyloxetane have been re‐examined and the published NMR assignments shown to be in error.
An NMR study of the conformations of certain alcohol derivatives of tricarbonyl(diene)iron compounds: A critique
Authors: Willcott M. R. , Bearden W. H. , Davis Raymond E. , Pettit R.
Published: May 2005

The initial assignments by Mahler and Pettit of relative configurations of the two racemic diastereomeric tricarbonyl‐(trans,trans‐3,5‐heptadien‐2‐ol)iron complexes and to the two racemic diastereomeric tricarbonyl‐(trans‐3,5‐hexadien‐2‐ol)iron complexes are consistent with NMR coupling constants, conformational analysis, previously reported Eu(fod)3 lanthanide‐induced shift data and new Yb(dpm)3 lanthanide‐induced shift data. A detailed discussion shows that, contrary to the claim by Foreman, the lanthanide‐induced shift data alone provide no new information regarding the relative configurations of these alcohols.
Semi‐empirical MO calculations of nuclear spin coupling constants
Authors: Barbieri Giorgio , Benassi Rois , Lazzeretti Paolo , Taddei Ferdinando
Published: May 2005

The results obtained using different semi‐empirical approaches, namely EHMO, IEHMO, CNDO/2 and INDO, in the calculation of spin–spin coupling constants within the framework of the one‐electron MO approximation are systematically compared in the case of several classes of organic molecules. While, at a semi‐empirical level SCF methods normally provide satisfactory wave function, the use of the simple EHMO seems better able to satisfy the problem connected with the calculation of spin–spin coupling constants, expecially when an appropriate set of AO's is chosen, in order to avoid parametrisation of Dirac monocentric integrals. Charge iteration (IEHMO) seems to improve the results slightly only when heteroatoms are present, but the complexity introduced into the calculations and the greatly increased computer time do not justify the slight improvement achieved, particularly as the method is applied to large molecules and organometallic compounds.
The proton magnetic resonance of heterocyclic diketones
Authors: Galasso V. , Pellizer G. , Lisini A. , Bigotto A.
Published: May 2005

A full analysis of the 60 MHz 1H NMR spectra of heterocyclic analogues of 1,3‐indandione [N‐(2‐bromoethyl)‐phthalimide, phthalic anhydride and thiophthalic anhydride] and of 1,2‐indandione (N‐methylisatin, coumarandione and 2,3‐dihydrothionapthene‐2,3‐dione) has been carried out. The protons of the symmetric compounds resonate at lower fields than those of the asymmetric ones and the proton ortho to the CO function is more deshielded than the proton ortho to the heteroatom. Coupled Hartree‐Fock perturbation theory has been applied to estimate the ring current contributions to the proton chemical shifts and to the magnetic susceptibilities. MO calculations based on the finite perturbation theory at the CNINDO levels provide information on the relative importance of σ and π pathways for the various coupling constants.
13C Fourier transform NMR and partially relaxed Fourier transform NMR relaxation study on the ethanol–manganese(II) system
Authors: Tiezzi E. , Valensin G.
Published: May 2005

The paramagnetic contribution to the 13C and 1H nuclear relaxation rates in the ethanol‐Mn(II) system has been calculated. Both T1 and T2 experiments have been performed by means of Fourier transform and partially relaxed Fourier transform NMR spectroscopy. The correlation times for the dipolar and scalar parts have been discussed and evaluated. Calculations of distances and of hyperfine coupling constants have been carried out.
29Si and 13C NMR studies of organosilicon chemistry. V—Sugar derivatives
Authors: Gale D. J. , Haines A. H. , Harris R. K.
Published: May 2005

29Si spectra have been obtained for four trimethylsilylated hexopyranoside sugars, and the resonance due to the CH2OSiMe3 group at position 5 has been assigned by experiments involving gated decoupling at a single 1H frequency.
Carbon‐13 chemical shifts and conformations of dimethylcyclohexanols
Authors: Pehk T. , Kooskora H. , Lippmaa E.
Published: May 2005

Carbon‐13 chemical shifts of all twenty‐two dimethylcyclohexanols, formed by the hydrogenation of isomeric xylenols, have been measured and assigned. Conformational peculiarities of dimethylcyclohexanols are discussed on the basis of their carbon‐13 chemical shifts.
13C NMR spectra of pyridinium betaines and related compounds
Authors: Takeuchi Yoshito , Dennis Nicholas
Published: May 2005

13C NMR spectra of 1‐methyl‐, 1‐phenyl‐ and 1, 6‐dimethyl‐pyridinium‐3‐oxide, 3‐methylphthalazinium 1‐oxide and anhydro‐3‐methanesulphonamido‐1‐methylpyridinium hydroxide, together with the corresponding amines and quaternary salts, were determined with and without proton noise‐decoupling. The assignment of resonances was based on the analysis of the fine splitting pattern caused by long range couplings whenever appropriate. A procedure for the estimation of chemical shifts of the salts and betaines is proposed.