Synthesis of β-Alkynyl Sulfonyl Fluorides from Olefins: A Fluorosulfonyl Radical Ternary Reaction via Metallo/Photoredox Synergy

Abstract

Click chemistry has boasted remarkable connectivity in molecule synthesis. The fluorosulfonyl group is not only an important structural motif in bioactive molecules, but also serves as a useful SuFExable group in the next-generation click chemistry, sulfur(VI) fluoride exchange (SuFEx) reactions. In this study, we successfully developed a facile synthetic approach to β-ethynyl sulfonyl fluorides, by leveraging the synergistic catalysis of photoredox and metal catalysis. Both aryl and alkyl terminal olefins can be readily converted into the desired products in good yields under visible light mediation by employing an irridium photocatalyst in combination with a copper catalyst. It is worth mentioning that potassium ethynyltrifluoroborate is also an usable alkynylation reagent for this transformation, which could afford a valuable terminal alkyne group. These products feature two distinct clickable reaction sites, which allows for efficient multiple linking of molecules by integrating the classic CuAAC click reaction with the SuFEx click reaction, and is demonstrated in molecule ligation with a natural product and a drug molecule, respectively.

Keywords

Sulfonyl fluorides / Radical fluorosulfonylation / Click chemistry / SuFEx reactions / Photocatalysis / Copper / Alkynes / Synergistic catalysis

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