Three‐Component Reaction of Potassium Alkyltrifluoroborates, Sulfur Dioxide and Allylic Bromides under Visible‐Light Irradiation

Abstract Diverse allylic sulfones are generated through a three‐component reaction of potassium alkyltrifluoroborates, sulfur dioxide and allylic bromides in the presence of 9‐mesityl‐10‐methyl acridinium perchlorate under visible light irradiation at room temperature. This transformation proceeds efficiently, and a broad reaction scope is demonstrated with good functional groups tolerance. This reaction is initiated by the treatment of potassium alkyltrifluoroborate under visible‐light irradiation in the presence of a photocatalyst, leading to alkyl radical. This alkyl radical intermediate is trapped by sulfur dioxide to provide alkylsulfonyl radical, which then undergoes further transformation to afford the corresponding allylic sulfone.