1H and13C nuclear magnetic resonance study of 1,3-dipyridylthioureas for chemical shift assignments and conformational analysis

1987 ◽  
Vol 25 (6) ◽  
pp. 474-479 ◽  
Author(s):  
L. V. Sudha ◽  
D. N. Sathyanarayana ◽  
S. Narasimha Bharati
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Conformational Analysis ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Nuclear Magnetic

Sesquiterpene alkaloids from Tripterygiumwilfordii (Hook): a nuclear magnetic resonance study of 1-desacetylwilfordine, 1-desacetylwilfortrine, and 2-debenzoyl-2-nicotinoylwilforine

1990 ◽  
Vol 68 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Li Ya ◽  
George M. Strunz ◽  
Larry A. Calhoun
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Root Extracts ◽  
C Nmr ◽  
Nuclear Magnetic

1-Desacetylwilfordine, 8, 1-desacetylwilfortrine, 9, and 2-debenzoyl-2-nicotinoylwilforine, 10, have been isolated from root extracts of the Chinese medicinal and insecticidal plant Tripterygiumwilfordii. Analysis of the 1H and 13C NMR spectra of 8 and 10, with the aid of COSY, HCCOSY, and COLOC experiments, has allowed unambiguous chemical shift assignments of all protons and carbons of these alkaloids. Keywords: alkaloids, sesquiterpene, Celastraceae, Tripterygium, NMR.

Nuclear Magnetic Resonance Study of Caesium-133 in Binary Molten Trifluoroacetate Salt Mixtures

2001 ◽  
Vol 56 (3-4) ◽  
pp. 288-290 ◽  
Author(s):  
V. N. Mirny ◽  
V. V. Trachevski ◽  
T. A. Mimaya
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Sodium Potassium ◽  
Salt Mixtures ◽  
Nuclear Magnetic

Abstract The chemical shifts of Cs+ in binary melts of caesium trifluoroacetate with lithium, sodium, potassium or thallium trifluoroacetates have been studied as a function of composition. An influence of added foreign cations on chemical shift of caesium nuclei has been found. The nature of the intra-and intermolecular paramagnetic contributions into the shifts of 133Cs is discussed.

A Carbon-13 Nuclear Magnetic Resonance Study of Chlorinated and Polyol Analogs of Glucose and Related Oligomers

1975 ◽  
Vol 53 (7) ◽  
pp. 1030-1037 ◽  
Author(s):  
Pierre Colson ◽  
Keith N. Slessor ◽  
H. J. Jennings ◽  
Ian C. P. Smith
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nuclear Magnetic Resonance Study ◽  
Substantial Decrease ◽  
Magnetic Resonance Study ◽  
Carbon Dissolution ◽  
Nuclear Magnetic

Complete assignments of the carbon-13 n.m.r. spectra of the following compounds in aqueous solution are presented: 6-chloro-6-deoxy-D-glucose, 6-O-methyl-D-glucose, ribitol, glucitol, 4-O-methyl-glucitol, maltose, maltitol, 6,6′-dichloro-6,6′-dideoxymaltose, 6′-chloro-6′-deoxy-maltose, isomaltose, isomaltitol, and 6′-chloro-6′-deoxyisomaltose. Some earlier assignments for maltose are reversed. Chlorination on the exocyclic carbon of the glucopyranose ring usually results in a substantial decrease in the chemical shift of the substituted carbon (−17 p.p.m.) and the next-nearest carbon (−1.2 p.p.m.); methylation leads to an increased chemical shift for the contiguous carbon (+10 p.p.m.) and only small changes for other carbons in the molecule. The response to 4-O-methylation in glucitol is opposite for C-3 (+0.7 p.p.m.) and C-5 (−0.8 p.p.m.) demonstrating that response of a particular carbon to substitution at a neighboring carbon depends upon the configuration of the particular carbon. Dissolution of these compounds in pyridine results in a bunching together of resonances which makes unambiguous assignments very difficult. The data for this series of compounds are useful in assigning the more complex spectra of microbial polysaccharides.

A carbon-13 nuclear magnetic resonance study of a series of 5-substituted benzimidazoles

1982 ◽  
Vol 60 (24) ◽  
pp. 2987-3092 ◽  
Author(s):  
Barry J. Blackburn ◽  
Douglas W. Ankrom ◽  
Harold M. Hutton
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Excess Charge ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Nmr Chemical Shift Assignments ◽  
Density Values

Carbon-13 nmr chemical shift assignments are reported for a series of 5-substituted benzimidazoles, 2-methylbenzimidazole, and 5,6-dimethylbenzimidazole. By employing the three-parameter equation of Smith and Proulx, the chemical shifts of all the ring carbons of the 5-substituted compounds are correlated with F and R of Swain and Lupton and Q of Schaefer; only the ipso carbon, C-5, has chemical shifts with a correlation coefficient less than 0.953. These correlations are compared with those obtained from the Swain–Lupton and Taft relationships; in general those from the latter two approaches are found to be less satisfactory. Correlations of the same chemical shifts with excess charge density values, calculated at the INDO level of approximation, are also presented.

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