Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication

Angew Chem Int Ed Engl. 2019 Sep 16;58(38):13318-13322. doi: 10.1002/anie.201906381. Epub 2019 Aug 2.

Abstract

Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions. Here, these two modalities are combined in an electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited-state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single-electron transfer (SET), resulting in C-H/N-H coupling with azoles. A rationale for the strongly oxidizing behavior of the photoexcited species is provided, while the stability of the catalyst is rationalized by a particular conformation of the cis-2,6-dimethylpiperidine moieties.

Keywords: C−H functionalization; Electrophotocatalysis; oxidation; radical dication; trisaminocyclopropenium ion.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Catalysis
  • Electron Transport / immunology*
  • Free Radicals / chemistry*
  • Humans

Substances

  • Free Radicals