Visible-light-mediated tandem sulfonylation/cyclization for the synthesis of oxindoles or quinazolinones via EDA complexes

-hydroxyphthalimide (TCNHPI) esters as electron acceptors and 1,4-diazabicyclo[2.2.2]octane-1,4-diium-1,4-disulfinate (DABSO) serving as both the electron donor and sulfur dioxide source, under metal- and photocatalyst-free conditions. Notably, this protocol exhibits excellent substrate compatibility and can be efficiently applied to the alkylsulfonylation of quinazolinones containing unactivated alkenes as well, delivering sulfonyl-substituted quinazolinones.