Thanks to CHactivation: 3‐Aryl‐3,4‐dihydroisoquinolines (2) are synthesized from bromobenzenes (1) by a sequence comprising a C(sp3)Hactivation, a Curtius rearrangement, and a tandem electrocyclic ring‐opening/6π electrocyclization. This method is applied to the synthesis of various isoquinoline‐containing molecules, including the tetrahydroprotoberberine alkaloid coralydine.