A metal-free multicomponent reaction involving readily available 1,8-enynes, benzoyl peroxide, and DABCO·(SO2)2 has been successfully developed. The desired products, sulfonylated indolo2,1-aisoquinoline derivatives, were obtained without the need for any catalysts or additives. In addition, this strategy utilizes readily available benzoyl peroxide as an aryl radical precursor, enabling the transformation through a sequential in situ SO2 insertion/Smiles rearrangement/radical cyclization relay process. Moreover, the transformation process is highly economical, facilitating the formation of multiple chemical bonds, including one C-N bond, two C-C bonds, and two C-S bonds in a single radical initiation.
Zhong et al. (Wed,) studied this question.