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Title
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Unexpected Products from Mesoionic 1,3-Thiazinium
and Oxazinium Olates: A Novel Access to 3,5-Diaryl-
1,3-thiazine-2,4,6-trione and Alkoxy-3,5-diphenyl-3H-
1,3-oxazine-2,6-dione Derivatives
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Keywords
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Mesoionic olates, (chlorocarbonyl)ketenes , 1,3-thiazine-2,4,6-trione
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Abstract
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The condensation of (chlorocarbonyl)ketenes 1 with N-phenylthiocarbamates 2 and N-phenylcarbamates 6 is postulated to
lead to the formation of unstable mesoionic 1,3-thiazinium 4-olates I or 1,3-oxazinium 4-olates II, respectively. At room
temperature, appropriately substituted mesoionic 1,3-thiazinium 4-olates I eliminated the corresponding alkene with
generation of 3,5-diaryl-1,3-thiazine-2,4,6-trione derivatives 3. However, the methoxy-substituted compound 5 was stable
at room temperature at least for several weeks. In the case of the mesoionic1,3-oxazinium 4-olates II an alkyl group
migration affords 4-alkoxy-3,5-diphenyl-3H-1,3-oxazine-2,6-diones 7.
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