摘要:

AbstractTemperature dependences of the paramagnetic shifts induced by Eu(fod)3in1H 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 × 10−8s at 14 °C and τp<1 × 10−8s at 20 °C, respectively. The corresponding activation energy is equal t

ISSN:0030-4921    

DOI:10.1002/mrc.1270071002

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractDie Diastereomeren von 16 1,3 Oxa‐, 1,3‐Aza‐und 1,3‐Thiophospholanen wurden mit Hilfe der Kopplungs‐konstanten2J(PCH) und3J(PCCH3), der Signalbreite der31P‐Signale und der1H‐chemischen Verschiebungen der CH3‐Gruppen zugeordnet. Es wird gezeigt, daß auch die31P‐chemischen Verschiebungen eine Bestimmung der relativen Konfiguration die

ISSN:0030-4921    

DOI:10.1002/mrc.1270071003

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effects of an hydroxy substituent on13C13C coupling constants and13C chemical shifts have been measured in 1‐hydroxynaphthalene‐2‐13C and 1‐hydroxypyrene‐1‐13C. The changes observed in the13C13C couplings show the effect of a substituent attached directly to the labelled carbon or to a carbonorthoto this. In both situations the effect is a decrease in the numerical magnitude of most of the long range13C13C c

ISSN:0030-4921    

DOI:10.1002/mrc.1270071004

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractDie chemischen Verschiebungen der1H‐NMR‐Spektren von 18 methylsubstituierten Cyclohexandicarbonsäure‐(1,2)‐anhydriden wurden bestimmt. Von den unsymmetrisch sub‐stituierten Verbindungen wurden die vicinalen Kopplungskonstanten ermittelt. Bei dentrans‐Anhydriden lässtsich aus den NMR‐Daten ableiten, dass der Sechsring in einer sesselähnlichen Form vorliegt. Auch bei dencis‐Anhydriden sind in den meisten Fällen Konformationen mit verdrillter Sesselanordnung des Cy

ISSN:0030-4921    

DOI:10.1002/mrc.1270071005

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractCarbon‐13 NMR spectra have been obtained for all‐trans‐N‐retinylidene‐n‐butylamine as an analogue of the Schiff's base linkage compound in visual pigment. The chemical shift changes on going from all‐trans‐retinal1to all‐trans‐N‐retinylidene‐n‐butylamine are observed. These changes indicate the collapse of the bond alternation in conjugated polyene carbons, whereas N‐protonation in all‐trans‐N‐retinylidene‐n‐butylamine

ISSN:0030-4921    

DOI:10.1002/mrc.1270071006

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractA series of perhydropyrido[1,2‐c][1,6,3]dioxazocines and 2‐alkylperhydropyrido[1,2‐c][1,3,6]oxdiazocines have been prepared. 6‐p‐Nitrophenyl‐3,4‐dimethylperhydropyrido[1,2‐c][1,6,3]‐dioxazodioxazocine is shown to adopt thecisfused ring conformation in solution with the nitrogen lone pair axial with respect to the piperidine ring. The 2‐alkylperhydropyrido[1,2‐c][1,3,6]oxdiazocines adopt a similarcisfused ring conformation and with increasing steric requirement of the 2‐alkyl substituent the 8‐membered ring increasingly favours the chair‐chair conformation, rather than the chair–boat conformation favoured by the

ISSN:0030-4921    

DOI:10.1002/mrc.1270071007

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe bianthraquinonic biological pigments luteoskyrin and rugulosin and five polyhydroxyanthraquinone derivatives are studied by carbon‐13 NMR in DMSO solution. Peak assignment for the fourteen carbon atoms of these compounds is achieved by proton spin decoupling and by investigating the effect of ionisation of the hydroxyl groups upon the carbon chemical shifts. Carbon chemical shifts in the planar hydroxyanthraquinones can be rationalised in terms of conjugation and intramolecular hydrogen bonding. The latter is responsible for the relative acidity of the hydroxyl groups in the analogues, and for the different conformations proposed for luteoskyrin and rugulosin. Tautomeric equilibria occur in DMSO and water–DMSO solutions for the anionic species [LS]2−and [RG]2−. This can account for the binding of luteoskyrin and rugulosin to nuclei

ISSN:0030-4921    

DOI:10.1002/mrc.1270071008

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe 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

ISSN:0030-4921    

DOI:10.1002/mrc.1270071009

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe synthesis ofcis‐ andtrans‐2‐(diethylaminomethyl)‐cyclohexanols and their structural assignments by NMR using the shift reagent Eu(dpm)3are 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 ofKare 452 and 420 for the two cyclohe

ISSN:0030-4921    

DOI:10.1002/mrc.1270071010

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractProton magnetic resonance spectra at 100 MHz are reported for theE‐ andZ‐isomers of pyridine‐2‐carbaldehyd 2′‐ pyridylhydrazone in carbon tetrachloride,d6‐dimethylsulphoxide andd6‐benzene solutions, and for various monomethylated derivatives ind6‐dimethylsulphoxide. The spectral parameters obtained by analysis with the help of LAOCOON 3 are discussed in terms of solvent effects and the chemical shift changes consequent upon isomerisation are evaluated. Some conclusions are reached concerning the preferred conformations of theE‐ andZ‐isomers of pyridine‐2‐carbald

ISSN:0030-4921    

DOI:10.1002/mrc.1270071011

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY