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13C-NMR study on the tautomerism of 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines between the hydrazone imine and diazenylenamine forms

✍ Scribed by Yoshihisa Kurasawa; Akiko Takano; Kyoko Kato; Ho Sik Kim; Yoshihisa Okamoto

Publisher
Journal of Heterocyclic Chemistry
Year
1997
Tongue
English
Weight
232 KB
Volume
34
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

The ^13^C‐nmr study was carried out for the tautomerism of the 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihy‐droquinoxalines 1a‐g and 2a‐e between the hydrazone imine A and diazenylenamine B forms, providing the carbon chemical shifts for the tautomers A and B of compounds 1a‐g and 2a‐e. The comparison of the carbon chemical shifts for the tautomer B of compounds 1d, 1f, and 2b in deuteriodimethyl sulfoxide with those in deuteriotrifluoroacetic acid showed that the C~4a~, C~5~, and diazenyl carbons were considerably shielded presumably due to the azo N‐deuteration in deuteriotrifluoroacetic acid.

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