Photoinduced oxidative cyclopropanation of ene-ynamides: synthesis of 3-aza[ n.1.0]bicycles via vinyl radicals

Chem Commun (Camb). 2021 May 27;57(43):5254-5257. doi: 10.1039/d1cc02016a.

Abstract

The first photoinduced synthesis of polyfunctionalized 3-aza[n.1.0]bicycles from readily available ene-ynamides and 2,6-lutidine N-oxide using an organic acridinium photocatalyst is reported. Applying a photocatalytic strategy to the reactive distonic cation vinyl radical intermediate from ynamide, a series of bio-valuable 3-azabicycles, including diverse 3-azabicyclio[4.1.0]heptanes and 3-azabicyclo[5.1.0]octanes that are challenging to accomplish using traditional methods, have been successfully synthesized in good to high yields under mild and metal-free conditions. Mechanistic studies are consistent with the photocatalyzed single-electron oxidation of ene-ynamide and the intermediacy of a putative cationic vinyl radical in this transformation. Importantly, this strategy provides new access to the development of photocatalytic vinyl radical cascades for the synthesis of structurally sophisticated substrates.

MeSH terms

  • Alkynes / chemistry*
  • Amides / chemistry*
  • Aza Compounds / chemical synthesis*
  • Aza Compounds / chemistry
  • Bridged Bicyclo Compounds / chemical synthesis*
  • Bridged Bicyclo Compounds / chemistry
  • Cyclopropanes / chemistry*
  • Molecular Structure
  • Oxidation-Reduction
  • Photochemical Processes

Substances

  • Alkynes
  • Amides
  • Aza Compounds
  • Bridged Bicyclo Compounds
  • Cyclopropanes
  • cyclopropane