A mechanistic investigation of the N-hydroxyphthalimide catalyzed benzylic oxidation mediated by sodium chlorite

Thomas Grunshaw, Susanna H. Wood, Stephen Sproules, Andrew Parrott, Alison Nordon, Peter D. P. Shapland, Katherine M. P. Wheelhouse, Nicholas C. O. Tomkinson

Research output: Contribution to journalArticlepeer-review

13 Downloads (Pure)

Abstract

A detailed investigation into the mechanistic course of N-hydroxyphthalimide catalyzed oxidation of benzylic centers using sodium chlorite as the stoichiometric oxidant is reported. Through a combination of experimental, spectroscopic, and computational techniques, the transformation is interrogated, providing improved reaction conditions and an enhanced understanding of the mechanism. Performing the transformation in the presence of acetic acid or a pH 4.5 buffer leads to extended reaction times but improves the catalyst lifetime, leading to the complete consumption of the starting material. Chlorine dioxide is identified as the active oxidant that is able to oxidize the N-hydroxyphthalimide anion to the phthalimide-N-oxyl radical, the proposed catalytically active species, which is able to abstract a hydrogen atom from the substrate. A second molecule of chlorine dioxide reacts with the resultant radical and, after loss of hypochlorous acid, leads to the observed product. Through a broad variety of techniques including UV/vis, EPR and Raman spectroscopy, isotopic labeling, and the use of radical traps, evidence for the mechanism is presented that is supported through electronic structural calculations.
Original languageEnglish
Pages (from-to)7933-7945
Number of pages13
JournalJournal of Organic Chemistry
Volume89
Issue number11
Early online date15 May 2024
DOIs
Publication statusPublished - 7 Jun 2024

Keywords

  • sodium chlorite
  • reaction conditions
  • oxidation

Fingerprint

Dive into the research topics of 'A mechanistic investigation of the N-hydroxyphthalimide catalyzed benzylic oxidation mediated by sodium chlorite'. Together they form a unique fingerprint.

Cite this