Relay photocatalytic cascade reactions: synthesis of indolo[2,1-a]isoquinoline derivatives via double C(sp3)-H bond functionalization.

A relay photoredox catalysis strategy concomitant with [1,5] hydrogen atom transfer has been applied in the construction of a biologically important indolo[2,1-a]isoquinoline framework via a cascade reaction. This reaction enables double C(sp3)-H bond functionalization and formation of two carbon-carbon double bonds from readily available starting materials in an efficient and step-economical manner.