摘要:

AbstractThe1H and13C NMR spectra of 9‐hydroxyphenalenone (1) and 9‐hydroxy‐2‐methylphenalenone (2) have been completely assigned. Primary and secondary deuterium isotope effects were determined in three solvents (chloroform, acetone and dimethyl sulphoxide), including the effect of temperature on the secondary isotope effects. Both negative and large long‐range secondary isotope effects were found for both 1 and 2. The average secondary isotope effects for corresponding carbons follow the same sign and magnitude pattern in both

ISSN:0749-1581    

DOI:10.1002/mrc.1260290112

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe structures of two pairs of tetrazole‐substituted spirostan steroids were characterized by the use of one‐ and two‐dimensional1H NMR measurements. The conformation of the seven‐membered spirostan ring A of the steroid was determined by analysis of proton spin coupling constants and confirmed by 1D and 2D NOE experiments showing interactions between the methyl group and ring protons. The conformation of the tetrazole‐substituted ring A was found to be the same for the four isomers, allowing them to be differentiated by the analysis of the effect of tetrazole‐ring isomerization on the chemical shifts of neighbour

ISSN:0749-1581    

DOI:10.1002/mrc.1260290113

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

Abstract77Se–77Se spin‐spin coupling constants of unsymmetrically and, for the first time, of symmetrically substituted diselenides have been measured for CF3SeSeCH3, CF3SeSeCF3, CF3SeSeCF2Cl and CF2ClSeSeCF2Cl. A correlation of the1J(SeSe) values with the average77Se shielding is found for perhalomethyl diselenides and organyl diselenides.77Se–13C coupling constants are also reported for the perhalomethyl diselenides. The coupling constants are much larger than in organyl diselenides. NMR data for the thioselenides CF3SeSR (R = CF3, CF2Cl, CFCl2, CCl3) are reported for comparison. It can be concluded that π‐type interactions occur in the SeSe or SeS bonds of diselenides and thioselenides, respectively, containing perhalom

ISSN:0749-1581    

DOI:10.1002/mrc.1260290114

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractMultinuclear NMR data are presented and discussed for a variety of vinylphosphines in which the vinyl group bears one, two or three substituents; these include organic and trimethylstannyl residues. The orientation of the phosphorus lone pair can be determined from two‐bond phosphorus‐carbon coupling constant values. The magnitudes of the3J(PCCSn),4J(PCCSnC) and5J(PCCSnCH) coupling constants are clearly determined by a throughspace interaction when P and C are in acisconf

ISSN:0749-1581    

DOI:10.1002/mrc.1260290115

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractCoherence transfer by MLEV‐16 isotropic mixing is shown to be an efficient way of obtaining phase‐sensitive heteronuclear chemical shift correlation 2D spectra. Both long‐ and short‐range correlations are possible by appropriate choice of mixing time. At long mixing times, the contribution of coherence transfer pathways through multiple couplings extends the range of correlation. Long mixing time experiments may therefore be useful for structure determination in total unknowns. Results are presented for a13C‐detected isotropic mixing experiment o

ISSN:0749-1581    

DOI:10.1002/mrc.1260290116

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe13C and1H chemical shift values of 31 cubanes ranging from mono‐ to hexa‐substituted derivatives were recorded in CDCl3solution and the spectra were fully assigned using, where necessary, 2D13C–H shift correlated spectra optimized for either one‐bond or long‐range13C–H couplings. The one‐bond13C–H coupling constants for the cubyl carbon resonances were also measure

ISSN:0749-1581    

DOI:10.1002/mrc.1260290117

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0749-1581    

DOI:10.1002/mrc.1260290119

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0749-1581    

DOI:10.1002/mrc.1260290101

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY