Exceptional isolation of both imine and enamine desmotropes of 4,1-benzothiazepines

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Abstract

The desmotropy of differently substituted (R*)-3-ethoxycarbonyl-2-aryl-3,5-dihydro-4,1-benzothiazepines and 3-ethoxycarbonyl-2-aryl-1,5-dihydro-4,1-benzothiazepines was investigated. The target 4,1-benzothiazepines were obtained via the ring transformation of (2R*,2aS*)-2-chloro-2a-aryl-2,2a-dihydro-2H,4H-azeto[1,2-a][ 3,1]benzothiazin-1-ones with sodium ethoxide in ethanol. The β-amino ester intermediate of the ring-enlargement reaction was isolated. Surprisingly, the desmotropes obtained could be separated by column chromatography and proved to be unexpectedly stable in solution. Further comparative studies revealed the existence of only the enamine forms of regioisomeric 2-ethoxycarbonyl-3-aryl-4,5-dihydro-7,8-dimethoxy-1,4-benzothiazepine derivatives; in this case, no desmotropy occurred. The structures were proved by means of NMR and IR spectroscopy.

Original languageEnglish
Pages (from-to)3207-3213
Number of pages7
JournalTetrahedron
Volume66
Issue number17
DOIs
Publication statusPublished - Apr 24 2010

Keywords

  • 1,4-Benzothiazepine
  • 4,1-Benzothiazepine
  • Desmotropy
  • Ring transformation
  • β-Lactam

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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