Synthesis of mesomeric betaines containing a pyrrolo- or imidazotriaziniumolate system and their cycloaddition with acetylenic dipolarophiles leading to triazocinone derivatives

Norio Sakai, Makoto Funabashi, Takayuki Hamada, Satoshi Minakata, Ilhyong Ryu, Mitsuo Komatsu*

*Corresponding author for this work

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

A series of 2-substituted mesomeric betaines containing a cyclic azomethine imine unit were synthesized and their cycloaddition with acetylenic dipolarophiles were examined. Unexpectedly, the cycloaddition of the betaines with electron-deficient dipolarophiles gave ring-expanding adducts having a triazocinone structure. With electron-rich dipolarophiles such as ynamines, the reactions proceeded more readily leading regioselectively to the same type of triazocinones in almost quantitative yields. In particular, in the case of an imidazobetaine and an ynamine, the cycloaddition took place at room temperature to afford the initial cycloadducts exclusively and in excellent yields. The isolated tricyclic precursors were found to rearrange quantitatively to the final products on heating to 60 °C.

Original languageEnglish
Pages (from-to)13703-13724
Number of pages22
JournalTetrahedron
Volume55
Issue number48
DOIs
StatePublished - 26 Nov 1999

Keywords

  • Cycloadditions
  • Medium-ring heterocycles
  • Mesoionic compounds
  • Rearrangements

Fingerprint Dive into the research topics of 'Synthesis of mesomeric betaines containing a pyrrolo- or imidazotriaziniumolate system and their cycloaddition with acetylenic dipolarophiles leading to triazocinone derivatives'. Together they form a unique fingerprint.

  • Cite this