Visible‐Light‐Promoted Photocatalyst‐Free Unsymmetrical Synthesis of Diaryl 1, 2‐Diketones from Terminal Alkynes/ Alkenes and Aryl Halides under the Formate‐Air‐DMSO Condition

A method has been developed for the synthesis of symmetrical and unsymmetrical aryl 1, 2‐diketones at room temperature, without the need for transition metals or photocatalysts. This protocol employs aromatic terminal alkynes or alkenes to react with aryl iodides under conditions involving formate, air, and DMSO. Mechanistic studies indicate that formate, air, and DMSO are all necessary conditions, and that the highly reactive carbon dioxide radical anion (CO2•−) generated under these conditions plays a key role in the reaction.