Intramolecular Acetyl Transfer to Olefins by Catalytic C−C Bond Activation of Unstrained Ketones

A rhodium‐catalyzed intramolecular acetyl‐group transfer has been achieved through a “cut and sew” process. The challenge arises from the existence of different competitive pathways. Preliminary success has been achieved with unstrained enones that contain a biaryl linker. The use of an electron‐rich N‐heterocycilc carbene (NHC) ligand is effective to inhibit undesired β‐hydrogen elimination. Various 9,10‐dihydrophenanthrene derivatives can be prepared with excellent functional‐group compatibility. The 13C‐labelling study suggests that the reaction begins with cleavage of the unstrained C−C bond, followed by migratory insertion and reductive elimination. Kreuzstich: Ein Rhodium‐katalysierter intramolekularer Acetylgruppentransfer wird durch „Schneiden und Nähen” des Moleküls erreicht. Ungespannte Enone, die ein Biaryl‐Zwischenstück enthalten, unterliegen einer C‐C‐Aktivierung unter der Wirkung einer temporären dirigierenden Gruppe. Verschiedene 9,10‐Dihydrophenanthren‐Derivate können mit zahlreichen funktionellen Gruppen hergestellt werden.