Some applications of 13C NMR spectroscopy in heterocyclic structure assignments

Nagarajan, K. (1985) Some applications of 13C NMR spectroscopy in heterocyclic structure assignments Proceedings of the Indian Academy of Sciences - Chemical Sciences, 95 (1-2). pp. 9-19. ISSN 0253-4134

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The usefulness of 13C NMR spectral data in solving otherwise intractable structural problems in heterocyclic chemistry is illustrated with ring systems such as imidazoles, pyrazoles, thiazoles, pyrimidines, benzodioxoles, benzodioxanes, benzoxazines, benzo-thiazines, quinoxalines, imidazopyrazoles, imidazothiazoles, pyridobenzoxazines, thiazolo-benzimidazoles, thiazinobenzimidazoles, pyrimidobenzimidazoles, naphthodioxanes and perimidines. For example, using both chemical shifts and coupling constants, especially the one across three bonds, it has been possible to assign unique structures to the addition products of acetylenedicarboxylic esters to a variety, of dinucleophiles such as thioureas, guanidines, 2-aminophenol, 2-aminothiophenol, 1,8-dihydroxy and 1,8-diaminonaphthalenes and 8-hydroxy-l,2,3,4-tetrahydroquinoline. These parameters also allow easy differentiation of isomeric imidazoles arising from N-alkylation of nitroimidazoles-or nitration of imidazoles and of isomeric pyrazoles obtained from the reaction of hydrazines with ethoxymethylene derivatives of 1,3-dicarbonyl compounds.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:13C Chemical Shifts; C-H Coupling Constants
ID Code:93500
Deposited On:19 Jun 2012 08:01
Last Modified:19 May 2016 06:34

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