An efficient procedure for the preparation of 3-acetyl-2,3-dihydrobenzothiazoles by ring contraction of 2,4-Diaryl-2,3-dihydro-1,5-benzothiazepines under acetylating conditions

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Reaction of 2,4-diaryl-2,3-dihydro-1,5-benzothiazepines 1 with a mixture of acetic anhydride and pyridine afforded 3-acetyl-2,3-dihydrobenzothiazoles 2 as sole products in good yields. Stereochemistry and the hindered rotation of the amide group were studied by means of NMR spectroscopy and the results were corroborated by AM1 calculations. A reaction mechanism for the ring contraction is proposed.

Original languageEnglish
Pages (from-to)995-998
Number of pages4
JournalLiebigs Annales
Issue number5
Publication statusPublished - May 1997



  • Acetylation
  • Benzothiazoles
  • NMR spectroscopy
  • Ring contractions
  • Structure elucidation

ASJC Scopus subject areas

  • Chemistry(all)

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