A metal-free four-component sulfonylation, Giese cyclization, selenylation cascade via insertion of sulfur dioxide.

We hereby report a highly regio- and diastereoselective arylsulfonylation-radical cyclization-selenylation cascade of alkynyl cyclohexadienones for the facile synthesis of highly functionalized dihydrochromenones. The protocol utilizes aryldiazonium salts as aryl partners and DABSO as a benign SO 2 source and also as a redox mediator. Additionally, we also developed a visible light mediated protocol wherein diaryliodonium salts were used as the aryl partners at room temperature.