Daisy-Chaining Photo- and Thermal Chemistry: Multi-Step Continuous Flow Synthesis of Visible-Light Mediated Photo-chemistry with a High Temperature Cascade Reaction

Luke D Elliott, Kevin I Booker-Milburn, Alastair J J Lennox*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

A highly efficient visible light mediated photochemical [2+2] cycloaddition is coupled with an atom economic thermal cascade reaction in a continuous flow process. By moving the photochemistry from UV to visible it is made more energy efficient and can be conducted with readily available equipment. The application of high-temperature flow chemistry to the thermal cascade step allows for safe and reliable scale-up with short reaction times. Thus, we demonstrate a rare example of a photo/thermal daisy-chained process and, specifically, the first visible light mediated excited state to thermal cascade reaction as a fully continuous process (20 g/h). The synthetic utility of flow chemistry is further showcased by the isolation of a reactive intermediate at quantities not possible under batch conditions.
Original languageEnglish
Pages (from-to)1943-1949
Number of pages7
JournalOrganic Process Research & Development
Volume25
Issue number8
Early online date19 Jul 2021
DOIs
Publication statusPublished - 20 Aug 2021

Bibliographical note

Funding Information:
We thank the EPSRC (EP/P013341/1 and EP/S018050/1) and the Royal Society (University Research Fellowship to AJJL) for funding, Steve Evans and Mark Ladlow (Uniqsis) for the loan of the FlowSyn and PhotoSyn reactors, and Paul Dinham and Paul Chappell (University of Bristol) for reactor construction.

Publisher Copyright:
© 2021 American Chemical Society.

Keywords

  • cascade
  • photochemistry
  • visible light
  • flow
  • Diels-Alder
  • rearrangement

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