Synthesis of 1,3-diaryl-3-trifluoromethylcyclopropenes by transition-metal-free reaction of 2,2,2-trifluoroacetophenone tosylhydrazones with alkynes: the effect of the trifluoromethyl group

Chem Commun (Camb). 2016 Mar 4;52(18):3677-80. doi: 10.1039/c5cc10472f.

Abstract

1,3-Diaryl-3-trifluoromethylcyclopropenes and 2-aryl- or 2-alkyl-1,3-diaryl-3-trifluoromethylcyclopropenes are prepared in a very simple way by reaction between 1,1,1-trifluoroacetophenone tosylhydrazones and terminal or internal alkynes, respectively, in a base promoted process that does not require the presence of any metal catalyst. The essential role of the trifluoromethyl group, which enables the formation of the cyclopropenes instead of the expected pyrazoles, has been computationally investigated, suggesting the participation of a free carbene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetophenones / chemistry*
  • Alkynes / chemistry*
  • Cyclopropanes / chemical synthesis*
  • Cyclopropanes / chemistry
  • Hydrocarbons, Fluorinated / chemical synthesis*
  • Hydrocarbons, Fluorinated / chemistry
  • Metals / chemistry*
  • Molecular Structure
  • Tosyl Compounds / chemistry*

Substances

  • Acetophenones
  • Alkynes
  • Cyclopropanes
  • Hydrocarbons, Fluorinated
  • Metals
  • Tosyl Compounds