Visible-Light-Mediated Ru-Catalyzed Synthesis of 3‑(Arylsulfonyl)but-3-enals via Coupling of α‑Allenols with Diazonium Salts and Sulfur Dioxide
journal contributionposted on 24.11.2020, 18:12 by Fernando Herrera, Amparo Luna, Pedro Almendros
The first coupling of α-allenols, sulfur dioxide, and arenediazonium salts is presented. The three-component reaction which is promoted by visible light can be easily accomplished using DABSO as a sulfur dioxide surrogate in the presence of a photoredox catalyst. In this manner, a broad range of electron-rich and electron-deficient aryl substituents are well accommodated in the sulfonylation–rearrangement cascade to afford the 2,2-disubstituted 3-(arylsulfonyl)but-3-enals in reasonable yields. Based on control experiments, a radical mechanism which does imply 1,2-aryl migration has been proposed.