Quinazolinones/Benzothiadiazines as Amidyl/Aminyl Radical Precursors for Controlled Cascade Cyclization via Photocatalyzed PCET.

Quinazolinones/benzothiadiazines were used as amidyl/aminyl radical precursors for cascade cyclizations via a photoredox-catalyzed proton-coupled electron transfer (PCET) process for the first time. A controlled synthesis of isoindole-fused quinazolinones/benzothiadiazines was carried out via quinazolinone amidyl/benzothiadiazine aminyl radical addition to the C-C triple bond under mild conditions. This transition-metal-free method provides an efficient and broad substrate scope for the synthesis of isoindole-fused quinazolinones/benzothiadiazines with step economy and atom efficiency.