CC BY 4.0 · SynOpen 2023; 07(01): 69-75
DOI: 10.1055/a-1995-1859
paper
Virtual Collection Click Chemistry and Drug Discovery

Photochemical Synthesis of Pyrazolines from Tetrazoles in Flow

Adam Burke
,
Silvia Spiccio
,
Mara Di Filippo
,
This research was supported by Science Foundation Ireland (12/RC2275_P2 and 18/RI/5702), the Royal Society of Chemistry (Research Enablement Grant; E20-2998), and the School of Chemistry through provision of a Sir Walter Hartley scholarship to M.D.F.


Abstract

Pyrazolines and their pyrazole congeners are important heterocyclic building blocks with numerous applications in the fine chemical industries. However, traditional routes towards these entities are based on multistep syntheses generating substantial amounts of chemical waste. Here we report an alternative approach using UV-light to convert tetrazoles into pyrazolines via a reagent-free photo-click strategy. This route generates nitrile imine dipoles in situ that are trapped with different dipolarophiles rendering a selection of these heterocyclic targets in high chemical yields. A continuous flow method is ultimately realized that generates multigram quantities of product in a safe and readily scalable manner thus demonstrating the value of this photochemical approach for future exploitations in industry.

Supporting Information



Publication History

Received: 24 November 2022

Accepted after revision: 07 December 2022

Accepted Manuscript online:
08 December 2022

Article published online:
22 February 2023

© 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by/4.0/)

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