Visible-light-induced photocatalyst-free cascade cyclization of 3-(2-(ethynyl)phenyl)quinazolinones to sulfonated quinolino[2,1- b ]quinazolinones.

A visible-light-induced K 2 S 2 O 8 -promoted cascade sulfonation/cyclization reaction was established using 3-(2-(ethynyl)phenyl)quinazolinones as efficient substrates under mild conditions. A series of sulfonated quinolino[2,1- b ]quinazolinones were successfully synthesized under transition-metal- and photocatalyst-free conditions. Notably, this strategy has the advantages of room temperature and simple operation, easy scale-up, and good functional group tolerance.