Photoinitiated Deaminative Alkylation/Cyclization for Rapidly Building Quinoxalino[2,1-<i>b</i>]quinazolinones via EDA Complexes

A visible-light-initiated deaminative alkylation/cyclization of isocyanophenylquinazolinones with Katritzky salts for the synthesis of polycyclic quinazolinone derivatives has been developed. This protocol features a broad substrate scope with 49 examples and efficient reaction conditions without additional catalysts and oxidants, which provides rapid access to pharmaceutically valuable analogues containing quinazolinone-fused compounds with yields up to 98% under 15 W blue LED irradiation for 0.5-3 h. The large-scale reaction of this method and the further transformations to useful polycyclic quinazolinones also afford positive results. Mechanism studies indicate that the formation of EDA complexes between Katritzky salts and DABCO initiates the reaction process.