A General Iron-Catalyzed Decarboxylative Oxygenation of Aliphatic Carboxylic Acids

Luca Mareen Denkler, Meghana Aladahalli Shekar, Tak Shing Jason Ngan, Luke Wylie, Dinar Abdullin, Marianne Engeser, Gregor Schnakenburg, Tobias Hett, Frank Hendrik Pilz, Barbara Kirchner, Olav Schiemann, Patrycja Kielb, Ala Bunescu

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We report an iron-catalyzed decarboxylative C(sp3)−O bond-forming reaction under mild, base-free conditions with visible light irradiation. The transformation uses readily available and structurally diverse carboxylic acids, iron photocatalyst, and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) derivatives as oxygenation reagents. The process exhibits a broad scope in acids possessing a wide range of stereoelectronic properties and functional groups. The developed reaction was applied to late-stage oxygenation of a series of bio-active molecules. The reaction leverages the ability of iron complexes to generate carbon-centered radicals directly from carboxylic acids by photoinduced carboxylate-to-iron charge transfer. Kinetic, electrochemical, EPR, UV/Vis, HRMS, and DFT studies revealed that TEMPO has a triple role in the reaction: as an oxygenation reagent, an oxidant to turn over the Fe-catalyst, and an internal base for the carboxylic acid deprotonation. The obtained TEMPO adducts represent versatile synthetic intermediates that were further engaged in C−C and C-heteroatom bond-forming reactions using commercial organo-photocatalysts and nucleophilic reagents.

Original languageEnglish
Article numbere202403292
JournalAngewandte Chemie International Edition in English
Volume63
Issue number32
DOIs
StatePublished - 5 Aug 2024
Externally publishedYes

Keywords

  • Carboxylic acid
  • Iron
  • Oxygenation
  • Photocatalysis
  • TEMPO

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