Photoinduced cyclization of aryl ynones with 4-alkyl-DHPs for the divergent synthesis of indenones, thioflavones and spiro[5.5]trienones

A direct and efficient visible-light-induced cascade cyclization reaction of aryl ynones with 4-alkyl-DHPs for the divergent synthesis of indenones, thioflavones and spiro[5.5]trienones via a 5-exo-trig or 6-exo-trig radical cyclization. This cascade reaction features operational simplicity, metal- and oxidant-free, and excellent functional group tolerance.