Functionalization of Alkynes and Alkenes Using a Cascade Reaction Approach: Synthesis of β-Keto Sulfones under Metal-free Conditions.

Here, we are reporting a multicomponent cascade reaction approach for the synthesis of β-keto sulfones by exploiting differential reactivity pattern of substrates under open-atmosphere and metal-free conditions. The coupling partners are aryldiazonium salts, unsaturated compounds, and DABSO. The optimized conditions worked well with both alkenes and alkynes. Moreover, the reaction also works with metabisulfite for the source of sulfone. The controlled liquid chromatography-mass spectrometry and 18O-labelled experiments suggested that air is a source of the incoming oxygen atom of the keto group of β-keto sulfones.