Recent advances in ring transformations of five-membered heterocycles and their fused derivatives

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42 Citations (Scopus)


Ring transformations of five-membered heterocycles and their benzologues for the recent 10 years are discussed and reviewed. These transformations are classified into four groups: (a) "classical ring transformations", where the starting and resulting ring system is of the same size, but the heteroatoms and/or their positions have been changed; (b) "degenerate ring transformations", where during the course of the transformation the starting compound and product have the same ring system, but the reaction proceeds by a ring opening and subsequent ring closure process; (c) "ring contractions" and "ring enlargements", where the sizes of the product rings are smaller or larger, respectively, than those of the starting compound; and (d) "pseudo ring transformation" or "ring-chain transfer", where the process is formally a ring transformation, but is realised by a ring closure of a side chain of the starting heterocycle and opening of the original ring. Reaction mechanisms of the most interesting ring transformations are also discussed.

Original languageEnglish
Pages (from-to)3405-3414
Number of pages10
JournalEuropean Journal of Organic Chemistry
Issue number18
Publication statusPublished - Sep 2001


  • Cyclizations
  • Heteroaromaticity
  • Isomerizations
  • Rearrangements
  • Ring opening

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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