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Synthesis 1996; 1996(11): 1375-1379
DOI: 10.1055/s-1996-4382
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Ring Transformation of 1,1-Dioxo-1,2-thiazine-6-carbaldehydes with Nitrogen Nucleophiles to Substituted Pyridine-3-sulfonanilides

E. Fanghänel1 , A. Hucke1 , Th. Lochter1 , U. Baumeister2 , H. Hartung2
  • 1Martin-Luther-Universität, Institut für Organische Chemie, D-06099 Halle, Germany, Fax +49(3461)462080
  • 2Martin-Luther-Universität, Institut für Physikalische Chemie, D-06099 Halle, Germany
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Publication Date:
31 December 2000 (online)

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1,1-Dioxo-1,2-thiazine-6-carbaldehydes 1 possessing a masked 1,5-dicarbonyl structure react with hydroxylamine with ring transformation to form the pyridine N-oxides 2. These can be deoxygenated with PCl3 to give the corresponding pyridine-3-sulfonanilides 3, which are available by the reaction of 1 with ammonia as well. The ring transformation of 1 with methylamine, benzylamine and hydrazine produces N-substituted mesoionic pyridinium salts 6-8. The cyclohexane-fused thiazine-6-carbaldehyde 9 can be transformed with ammonia to the 5,6,7,8-tetrahydroquinoline 10. Reaction of 2 with NaNO2/HCl enables the introduction of the nitro group into the anilide part of the molecule.

ring transformation - 1,1-dioxo-1,2-thiazine-6-carbaldehydes - pyridine-3-sulfonanilides - mesoionic pyridinium salts - nitration with NaNO2/HCl