ISSN:0030-4921    

DOI:10.1002/mrc.1270080811

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

Abstract13C n.m.r. single‐frequency off‐resonance decoupled (sford) CH multiplet resonance which deviate from normally assumed, isolated AnX spin descriptions have been characterized. Methylene carbons whose appended protons are nonequivalent generate doublets of doublets in sford spectra provided the proton chemical shift difference exceedsc.3 × (Jgem). The isolated moiety–CHH′–closely approximates an AMX spin system. The strong chemical shift nonequivalence of geminal aminomethylene protons induced by the nitrogen lone pair in someN‐substituted piperidine derivatives is accompanied by preferential modification of the one‐bond CH coupling constants of the α‐amino protons. InN‐methyl‐4‐t‐butylpiperidine the natural coupling constants were shown to differ by 6–12 Hz. The13C sford resonances of protonated carbons display varying degrees of second‐order coupling depending on the coupling strength of a carbon's appended protons with a strongly coupled spin set, the number of nuclei in the spin set, and the magnitude of the carbon's residual one‐bond splitting. Qualitative criteria that allow the classification of degrees of second‐order coupling have been established and utilized in sig

ISSN:0030-4921    

DOI:10.1002/mrc.1270080802

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractLes spectres de RMN du proton d'une série de dérivés des méthyl‐4 (ou phényl‐4) dioxa‐ et dithiaphospholanes‐1,3,2 sont analysés. La configuration de ces composés est précisée. L'angle de torsion de la liaison C4C5est calculée et la conformation du cycle à l'état

ISSN:0030-4921    

DOI:10.1002/mrc.1270080803

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractLes spectres de RMN du proton de quelques nouveaux oxazaphosphorinanes‐1,3,2 sont analysés. La stéréochimie et la conformation du cycle sont précisées. La valeur de l'enthalpie libre conformationnelle et de l'angle de torsion des liaisons C‐4C‐5 et C‐5C‐6 est calculée pour quelques uns de ces oxazap

ISSN:0030-4921    

DOI:10.1002/mrc.1270080804

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe13C n.m.r. spectra of some dimericCatharanthusalkaloids are reported and assigned. Methods devised to aid in the assignment of resonances in complex molecules are described. The13C n.m.r. spectra of several derivatives of vinblastine are discussed.

ISSN:0030-4921    

DOI:10.1002/mrc.1270080805

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractA tabulation has been compiled for twenty13CH coupling constants of various carboxylic acids and includes2J(C,H),3J(C,H) and4J(C,H) values of olefins (bothcisandtrans);3J(C,H),4J(C,H) and5J(C,H) values of aromatics;3J(C,H) and4J(C,H) values of acetylenes; and2J(C,H) and3J(C,H) values of rigid aliphatics. This tabulation has been completed in the present study by the spin‐tickling proton n.m.r. study of13C‐carboxyl‐endo‐1,2,3,4,7,7‐hexachloronorbornene‐5‐carboxylic acid, which has established that the2J(C,H) value is negative and the3J(C,H) values (bothcisandtrans) are positive in this system. A plot of these twentyJ(C,H) values vs the correspondingJ(H,H) values of geometrically equivalent model systems (where there is a proton in place of a carboxyl group) gives a correlation coefficient of 0·975 (with a slope of 0·62), indicating that carbon–proton and proton–proton couplings operate by similar mechanisms throughout this broad serie

ISSN:0030-4921    

DOI:10.1002/mrc.1270080806

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractAn extensive carbon‐13 nuclear magnetic resonance study of selected model olefins dissolved in deuteriochloroform has been carried out under standardized conditions. Assignments of the chemical shifts have been made. The influence of the nature of the solvent and the effect of changing the concentration of the solute have been investigated. The results are intended to provide a practical aid for the analysis of olefinic material

ISSN:0030-4921    

DOI:10.1002/mrc.1270080807

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe amounts of boat (A) and planar (B) forms for the equilibrium state in D2O and CD3OD/d6‐DMSO (1:1) were calculated for seven proline‐containing cyclic dipeptides from their13C n.m.r. spectra. For c‐Pro‐Val the thermodynamic functions for the conversion between the boat and planar forms have been obtained from measurements of equilibrium constants at different tempe

ISSN:0030-4921    

DOI:10.1002/mrc.1270080808

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe intermolecular Overhauser effect {1H}13C is studied on two binary systems chloroform/carbon disulfide and chloroform/acetone. Some comments are made concerning the use of these measurements for the study of intermolecular interactions in solutio

ISSN:0030-4921    

DOI:10.1002/mrc.1270080809

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe15N13C coupling constants in15N labelled azaadamantane have been measured and interpreted in terms of their conformational dependence as compared with15N‐quinuclidin

ISSN:0030-4921    

DOI:10.1002/mrc.1270080810

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY