Telescoped Continuous Flow Synthesis of 2-Substituted 1,4-Benzoquinones via Oxidative Dearomatisation of para-Substituted Phenols Using Singlet Oxygen in Supercritical CO2

Bruna L. Abreu, Hamza Boufroura, Jonathan C. Moore, Martyn Poliakoff, Michael W. George

Research output: Journal PublicationArticlepeer-review

Abstract

This paper describes a continuous multi-step synthesis in supercritical CO2. A continuous flow synthesis of 2-substituted 1,4-benzoquinones is reported, and details of the high-pressure reactors are given. This proceeds via the telescoped dearomatisation of p-substituted phenols using singlet oxygen in supercritical CO2 and an acid-mediated C-C migration. The process has a short residence time of 30 minutes, with overall yields and projected productivities of up to 83% and 9 g/day, respectively. This methodology enables a safe and efficient synthesis of 2-substituted 1,4-benzoquinones from photo-generated singlet oxygen, and cheap and readily available p-substituted phenols. The procedure has high atom efficiency, low photocatalyst loading, and substitutes potentially hazardous and corrosive reagents and solvents for molecular oxygen, CO2, and the less hazardous solid-supported acid Amberlyst-15.

Original languageEnglish
JournalSynthesis (Germany)
Early online date12 May 2022
DOIs
Publication statusPublished Online - 12 May 2022
Externally publishedYes

Keywords

  • 1,4-benzoquinones
  • continuous flow
  • dearomatization
  • para-substituted phenols
  • photooxidation
  • singlet oxygen
  • supercritical CO
  • telescoped synthesis

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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