Synthesis of β‐Keto Sulfones by a Catalyst‐Free Reaction of Aryldiazonium Tetrafluoroborates, Sulfur Dioxide, and Silyl Enol Ethers

A green approach for the generation of β-keto sulfones through a reaction of aryldiazonium tetrafluoroborates, sulfur dioxide, with silyl enol ether under catalyst-free and additive-free conditions is realized. This reaction proceeds efficiently at room temperature, and goes to completion in half an hour. During the reaction process, aryldiazonium tetrafluoroborate would react with DABCO.(SO2)2 to provide sulfonyl radical as the key intermediate, which would initiate the transformation. Oxidants or metal catalysts are avoided, and the presence of DABCO plays an important role in the reaction as well.