摘要:

AbstractChiral NMR recognition of terpenic and similar hydrocarbons by Ag(fod) and optically active lanthanide shift reagents is described. Twenty‐four1H signals of eight compounds and, as a first report in the literature, eleven13C signals of three compounds were split into signal pairs due to the respective enantiomers. Although the magnitudes of the splittings are not connected to the structure of the substrate molecules in an obvious manner, the configurations of the similar compounds camphene andepi‐β‐santalene were related empirically. All spectra were sufficiently resolved to allow separate integration of enantiomer signals; from the integrals the enantiomeric purities of seven non‐racemic mixtures were determined with good accuracy. The shift curves made several hitherto unknown assignments

ISSN:0030-4921    

DOI:10.1002/mrc.1270220602

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

Abstract31P NMR measurements were performed in order to study the intracellular phosphate pools of the green algaChlorella fusca. Cells of asynchronous cultures contain a large pool of polyphosphates, whereas the amount of polyphosphates in cells of synchronous cultures depends on the state of differentiation. The assignment of extracellular and intracellular inorganic orthophosphate is achieved by changing the pH, whereas the intracellular compartmentation of inorganic orthophosphates and sugar phosphates is shown during irradiation of the cells with light within the NMR spectrometer.

ISSN:0030-4921    

DOI:10.1002/mrc.1270220603

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

AbstractThe positions of conformational equilibrium in disubstituted arene chromium tricarbonyl complexes, i.e. alkylanisole chromium tricarbonyl complexes and alkylbenzoate chromium tricarbonyl complexes, have been determined by1H NMR spectroscopy. It has been found that the donor effect is the dominant factor in determining the preferred conformation.

ISSN:0030-4921    

DOI:10.1002/mrc.1270220604

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

Abstract1H,13C,14N and199Hg NMR data were obtained for organomercury fulminates, RHgCNO (R  Me, Ph, CNO). The relatively slow relaxation processes effective for the quadrupolar nitrogen muclei of these compounds allow the detection of199Hg14N scalar coupling constants. This feature is ascribed to the presence of low electric field gradients around the14N nucleus, owing to the presence of the mercury atom. In mercury fulminate, the199Hg nucleus appears to be coupled with two equivalent14N nuclei, thus indicating the existence of a covalent structure Hg(CNO)2in solut

ISSN:0030-4921    

DOI:10.1002/mrc.1270220605

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

AbstractIntensity modulated31P NMR spectra were obtained using the pulse sequence published by Patt and Shoolery. This attached proton test (APT) technique for signal assignment could be applied to systems with long‐range heteronuclear couplings in POCH fragments. In a model system derived from the alcoholysis of P4S10the six reaction products were assigned to the six signals in the31P NMR s

ISSN:0030-4921    

DOI:10.1002/mrc.1270220606

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

AbstractThe13C NMR spectra of the isomeric alkaloids lupinine and epilupinine and their perchlorates, methiodides andN‐oxides are discussed. Chemical shift changes due to protonation, quaternization andN‐oxidation are analysed. Thetrans‐quinolizidine ring fusion is proved for epilupinine salts and for theN‐oxide. Lupinine also exists predominantly with thetransring fusion, but thecisring fusion is found in the methiodide. An equilibrium of two stereoisomers, one withtrans‐ and the other withcis‐ring fusion, has been established for lupinine perchlorate in D2O solution. LupinineN‐oxides isolated in the crystalline state are shown to have bothtrans‐ and the

ISSN:0030-4921    

DOI:10.1002/mrc.1270220607

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

AbstractLong‐range proton–proton coupling constants between the hydroxy proton and ring protons were employed to deduce the conformational preferences of 1‐ and 2‐hydroxynaphthalene. 2,6‐Dibromo‐1,5‐dihydroxy‐naphthalene, 2‐acetyl‐1‐hydroxynaphthalene, 1,6‐dibromo‐2‐hydroxynaphthalene and 2‐hydroxy‐1‐naphthaldehyde were used as model compounds. Molecular orbital calculations at the CNDO/2 and INDO level were used to calculate the energy and the long‐range proton–proton coupling of different conf

ISSN:0030-4921    

DOI:10.1002/mrc.1270220608

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

Abstract13C Chemical shifts are reported for the ruthenium(II) tris complexes of thirteen 2,2′‐bipyridyls and three 1,10‐phenanthrolines and for the osmium(II) tris complexes of five 2,2′‐bipyridyls. Chelation induced shifts (δcomplex– δligand) are discussed in terms of models for π back‐bonding.13C NMR is shown to be a convenient tool for the direct observation of the geometrical isomerism of complexes formed from monosub

ISSN:0030-4921    

DOI:10.1002/mrc.1270220609

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

Abstract1H NMR spectra recorded at 400 MHz of the enkephalin analogues Tyr‐D‐NIe‐Gly‐Phe‐D(andL)‐NIeS and the dipeptide Ac‐Phe‐D‐NIeS as solutes in DMSO‐d6are reported and assigned. A preferred conformation of theD2L5peptide is proposed, based on evidence of an intramolecular hydrogen bond between Phe4NH and Tyr1CO and NH/a‐CH coupling constants. The possibility of conformational differences between the isomeric peptides accounting for differences in their ability to bind to δ‐opiat

ISSN:0030-4921    

DOI:10.1002/mrc.1270220610

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY

摘要:

AbstractEpimeric mixtures of isoxazolidine derivatives were investigated by1H NMR spectra obtained in the presence of lanthanide shift reagents. The NMR signals of all the components contained in a mixture of 2,3‐diphenyl‐5‐carboxymethylisoxazolidines were identified and the LISCA computer program enabled the stereochemistry of the different isomers to be establ

ISSN:0030-4921    

DOI:10.1002/mrc.1270220611

出版商:John Wiley&Sons Limited    

年代:1984

数据来源: WILEY