Bench stable diarylmethylium salts as catalysts in the light mediated hydrosulfonylation of alkenes Polyssena Renzi, Emanuele Azzi, Sylvain Ascensio, Stefano Parisotto, Fabrizio Sordello, Francesco Pellegrino, Giovanni Ghigo, Annamaria Deagostino Department of Chemistry, University of Torino, Italy Displaying a plethora of activities, sulfur-based molecules have a pivotal role as functional groups in many natural products and organic materials. Above all, they are of particular interest for the pharmaceutical industry, 1 with more than 150 sulfur-containing drugs available on the market. For these reasons, the development of milder and greener methodologies for the formation of C–S bonds has been the object of intensive work for organic chemists. Currently in this field, photocatalysis has gained a central role opening peculiar reactivities, barely possible by traditional thermal transformations. As concerns hydro/sulfonylation reactions, photocatalyzed methodologies are dominated by the employment of iridium-based complexes, allowing the sulfonyl radical to be generated from different precursors. 2 In this framework, we propose the replacement of expensive iridium catalysts with novel bench-stable diarylmethylium salts. 3 For the first time, these compounds were employed as organo-photocatalysts showing high activity at only 1% catalyst loading. This operationally simple methodology, not requiring anhydrous conditions, allowed the synthesis of more than 40 functionalised sulfones with a remarkable functional group tolerance and scalability up to 15 mmols, including also natural products and biological active molecules. Experimental and computational mechanistic studies revealed that the key sulfonyl radical can be formed through an innovative mechanism.
Figure : Hydro/sulfonylation of alkenes mediated by diarylmethylium salts. References 1. M. Feng, B. Tang, S. H. Liang, X. Jiang, Sulfur Containing Scaffolds in Drugs: Synthesis and Application in Medicinal Chemistry, Curr. Top. Med. Chem. 2016, 16, 1200–1216. 2. G. Qiu, K. Zhou, L. Gao, J. Wu, Insertion of sulfur dioxide via a radical process: an efficient route to sulfonyl compounds, Org. Chem. Front. 2018, 5, 691–705. 3. Renzi, E. Azzi, S. Ascensio, S. Parisotto, F. Pellegrino, G. Ghigo, A. Deagostino, Inexpensive and bench stable diarylmethylium tetrafluoroborates as organocatalysts in the light mediated hydrosulfonylation of unactivated alkenes, Chem. Sci. 2023, 14, 2721-2734.
P57
© The Author(s), 2023
Made with FlippingBook Learn more on our blog