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53 results on '"13c label"'

51. Carbon-13 nuclear magnetic resonance assignments and biosynthesis of the mycotoxin ochratoxin A

Author

Pieter S. Steyn, Amelia E. de Jesus, Philippus L. Wessels, and Robert Vleggaar

Subjects
Ochratoxin A, chemistry.chemical_compound, Nuclear magnetic resonance, Biosynthesis, chemistry, 13c label, Carbon-13, food and beverages, Moiety, Mycotoxin
Abstract

The 13C n.m.r. spectrum of ochratoxin A has been assigned. The distribution of 13C label and of intact acetate units, as determined from the 13C n.m.r. spectra of ochratoxin A derived from singly and doubly labelled [13C]acetate, defines the biosynthetic origin of the 3,4-dihydro-(3R)-methylisocoumarin moiety unequivocally.

Published
1980
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52. Carbon-13 nuclear magnetic resonance assignments and biosynthesis of versicolorin A in Aspergillus parasiticus

Author

De Buys Scott, Charles P. Gorst-Allman, Pieter S. Steyn, and Philippus L. Wessels

Subjects
Aflatoxin, chemistry.chemical_compound, Nuclear magnetic resonance, biology, Biosynthesis, chemistry, 13c label, Carbon-13, Anthraquinones, Absolute configuration, biology.organism_classification, Aspergillus parasiticus
Abstract

The 13C n.m.r. spectrum of versicolorin A has been assingned. The distributions of 13C label and of the intact acetate units have been determined from the 13C n.m.r. spectra of versicolorin A derived from singly and doubly labelled [13C]acetate. The biosynthesis of versicolorin A in relation to that of previously determined C20 anthraquinones and aflatoxin B1 is discussed. The absolute configuration of versicolorin A is deduced.

Published
1978
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53. Addition reactions of heterocyclic compounds. Part LIX. A 13C tracer study of the mechanism of formation of azepines from 2-methyl-quinolines and dimethyl acetylenedicarboxylate

Author

Rowena F. Flowerday and R. Morrin Acheson

Subjects
Dimethyl acetylenedicarboxylate, chemistry.chemical_compound, Addition reaction, chemistry, Stereochemistry, 13c label, Medicinal chemistry, Methyl group
Abstract

A 13C label in the methyl group of 2-methylquinoline and its 6-bromo-derivative was found at position 10 or 11 of the azepino[1,2-a]quinolines formed in reactions with dimethyl acetylenedicarboxylate. This excludes a reaction pathway involving an ester shift but is consistent with the possibility of a spiro intermediate.

Published
1975
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