Copper-Catalyzed Cyclization/Dimerization of Tryptamines with O2/Air as the Sole Oxidant: Direct Access to Complex Bispyrrolidino[2,3- b]indoline

J Org Chem. 2021 Dec 3;86(23):17164-17172. doi: 10.1021/acs.joc.1c02277. Epub 2021 Oct 28.

Abstract

The first transition metal catalytic one-step synthesis of the 3a, 3a'-bispyrrolidino [2,3-b] indoline scaffold via tandem cyclization/dimerization of tryptamines has been realized with the environmentally friendly O2/air as the sole oxidant. Different from the traditional direct oxidation of indole "N-H" group by excess amount of metal salts, a copper-catalyzed oxidative cyclization reaction is developed for the formation of the radical pyrrolidinoindoline intermediate in the current strategy. The robustness and practicality of this methodology is demonstrated by the step-economic, divergent total synthesis of natural products (±)-folicanthine and meso-folicanthine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Copper*
  • Cyclization
  • Dimerization
  • Indoles
  • Oxidants
  • Tryptamines*

Substances

  • Indoles
  • Oxidants
  • Tryptamines
  • indoline
  • Copper