Thermal transformations of 2H-benzimidazole 1,3-dioxides

Abstact Thermal transformations of 2 H -benzimidazole 1,3-dioxides represented by spiro[2 H -benz-imidazole-2,1′-cyclohexane] 1,3-dioxide and its 5-nitro derivative were studied. Their heating resulted in reversible isomerization to spiro[3 H -[2,1,4]benzoxadiazine-3,1′-cyclohexane] 4-oxides. More p...

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Veröffentlicht in:Russian chemical bulletin Jg. 60; H. 8; S. 1723 - 1728
Hauptverfasser: Samsonov, V. A., Bagryanskaya, I. Yu, Gatilov, Yu. V., Savel’ev, V. A.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Boston Springer US 01.08.2011
Schlagworte:
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Full Articles
Inorganic Chemistry
Organic Chemistry
2
heterocyclic N-oxides
rearrangements
oxidation
benzimidazoles
2,1,4-benzoxadiazines
phototransformation
ISSN:1066-5285, 1573-9171
Online-Zugang:Volltext
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Zusammenfassung:Abstact Thermal transformations of 2 H -benzimidazole 1,3-dioxides represented by spiro[2 H -benz-imidazole-2,1′-cyclohexane] 1,3-dioxide and its 5-nitro derivative were studied. Their heating resulted in reversible isomerization to spiro[3 H -[2,1,4]benzoxadiazine-3,1′-cyclohexane] 4-oxides. More prolonged heating of 2 H -benzimidazole 1,3-dioxides caused sequential elimination of the first and then (at higher temperature) the second N-oxide oxygen atom to form 2 H -benzimidazole derivatives, which upon further heating were transformed to 7,8,9,10-tetrahydro-6 H -azepino[1,2- a ]benzimidazoles. A scheme of the process was suggested, which described the experimental data obtained. Spiro[3 H -[2,1,4]benzoxadiazine-3,1′-cyclohexane] 4-oxides on exposure to the sunlight were quantitatively transformed to 2 H -benzimidazole 1,3-dioxides.
ISSN:1066-5285
1573-9171
DOI:10.1007/s11172-011-0257-x