Visible-light-induced aerobic dearomative reaction of indole derivatives: access to heterocycle fused or spirocyclo indolones.

Oxazolo[3,2-a]indolone and spiro[furan-2,2'-indolin]one are synthesized by the visible-light-induced aerobic dearomative reaction of indoles. The common indole tethered alcohol at the N1 or C2 position reacts in a cascade fashion, providing facile access to diverse indolone scaffolds.