Triaryl Carbonium Ion-Pair-Mediated Cooperative Aerobic Dehydrogenation of N-Heterocycles

Zhenguo Zhang, Jun Gu, Liang Ji, Xiaoxiao Liu, Ting Zhang, Yongheng Lv, Fang Liu, Zhenhua Jia, Teck Peng Loh

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The triphenylmethyl radical was discovered by Gomberg in 1900 and has been shown to be a persistent radical species. Surprisingly, this radical is rarely used in organic synthesis since its discovery over a century ago. Here, we report a metal-free aerobic dehydrogenation of N-heterocycles mediated by a triphenylmethyl radical generated from a triaryl carbonium ion pair as the precatalyst in the presence of TEMPO. This protocol exhibits a broad substrate scope and excellent functional group tolerance. The practicality has also been demonstrated with the gram-scale preparation of key intermediates of small-molecule drugs and late-stage functionalization of various dipine drugs. Mechanistic studies and DFT calculations revealed that the triphenylmethyl radical was involved in the catalytic cycle and was essential for the aerobic dehydrogenation process.

Original languageEnglish
Pages (from-to)14123-14129
Number of pages7
JournalACS Catalysis
Volume12
Issue number22
DOIs
StatePublished - 18 Nov 2022

Keywords

  • N-heterocycles
  • aerobic dehydrogenation
  • cooperative catalysis
  • ion pair
  • metal free

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