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 SO2 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.

Automated summary

We report a highly selective cascade reaction for the synthesis of highly functionalized dihydrochromenones. The reaction involves arylsulfonylation, radical cyclization, and selenylation of alkynyl cyclohexadienones. Aryldiazonium salts and DABSO are used as reactants, with DABSO also serving as a benign SO2 source and redox mediator. A visible light mediated protocol using diaryliodonium salts as reactants was also developed.