Direct Synthesis of Fluorescent Oxazolo-phenoxazines by Copper-Catalyzed/Hypervalent Iodine(III)-Mediated Dimerization/Cyclization of 2-Benzylamino-phenols

J Org Chem. 2022 Jan 21;87(2):1032-1042. doi: 10.1021/acs.joc.1c02329. Epub 2022 Jan 11.

Abstract

A dimerization/cyclization reaction of 2-benzylamino-phenols for the direct synthesis of the oxazolo-phenoxazine skeleton is reported. The reaction occurs under copper catalysis in the presence of hypervalent iodine(III), giving selectively the 5H-oxazolo[4,5-b]phenoxazine compounds. The cascade process, which allows the conversion of the substrates into the tetracyclic products, involves three C-H functionalization steps. Initial oxidation of electron-rich arenes by the hypervalent iodine is essential for the dimerization of substrates, whereas the formation of the five-membered rings is promoted by the copper species. 1-Benzyl-2-phenyl-6-(aryl-benzyl)amino-benzimidazoles are regioselectively obtained using N,N'-dibenzyl-phenylenediamines as starting substrates. The fluorescence emission properties of these classes of products have been evaluated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Copper*
  • Cyclization
  • Dimerization
  • Iodine*
  • Oxazines
  • Phenols

Substances

  • Oxazines
  • Phenols
  • Copper
  • Iodine
  • phenoxazine