Visible‐Light‐Induced Tandem Cyclization of 1,7‐Enynes to Access Phenanthridin‐6(5<i>H</i>)‐Ones Using a Polydimethylsiloxane (PDMS) Based Microreactor

Abstract We report an organophotoredox‐catalyzed visible‐light‐induced tandem cyclization of 1,7‐enynes with diaryliodoniumtriflates has been established leading to Phenanthridin‐6(5 H )‐one derivatives under metal‐free conditions. This transformation is initiated by visible light induced aryl radical formation from diaryliodoniumtriflates, followed by its regioseletive addition to the acrylate moiety of 1,7‐enynes then undergoes intramolecular 6‐exo‐dig cascade radical annulation and which is terminated by single electron oxidation along with proton abstraction. This effective, sustainable and metal‐free protocol exhibits a broad substrate scope and excellent tolerability towards various functional groups in good to excellent yields. Further implementation of a batch protocol to continuous flow protocol utilizing polydimethylsiloxane (PDMS) based microreactor exhibits its efficiency.