Visible Light Mediated Photocatalytic N‑Radical Cascade Reactivity of γ,δ-Unsaturated N‑Arylsulfonylhydrazones: A General Approach to Structurally Diverse Tetrahydropyridazines

Tetrahydropyridazines are of particular interest for their versatility as intermediates in organic synthesis and display pharmacological activity in several domains. Here, we describe the photocatalytic synthesis of different tetrahydropyridazines starting from γ,δ-unsaturated N-arylsulfonylhydrazon...

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Bibliographic Details
Published in:Journal of organic chemistry 2021-02, Vol.86 (4), p.3300-3323
Main Authors: Azzi, Emanuele, Ghigo, Giovanni, Parisotto, Stefano, Pellegrino, Francesco, Priola, Emanuele, Renzi, Polyssena, Deagostino, Annamaria
Format: Article
Language:English
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Summary:Tetrahydropyridazines are of particular interest for their versatility as intermediates in organic synthesis and display pharmacological activity in several domains. Here, we describe the photocatalytic synthesis of different tetrahydropyridazines starting from γ,δ-unsaturated N-arylsulfonylhydrazones. Simple structural changes of substrates result into three different pathways beginning from a common N-hydrazonyl radical, which evolves through a domino carboamination/dearomatization, a HAT process, or a photoinduced radical Smiles rearrangement to afford diverse tetrahydropyridazines. All reactions are carried out in very mild conditions, and the quite inexpensive [Ru­(bpy)3]­Cl2 is used as the catalyst. Preliminary mechanism studies are presented, among them luminescence and electrochemical characterization of the involved species. Computational studies allow to rationalize the mechanism in accord with the experimental findings.
ISSN:0022-3263
1520-6904
1520-6904
DOI:10.1021/acs.joc.0c02605