Frontispiece: Stereocontrolled Synthesis of Benzo[k]fluoranthenes-An Unexpected Isomerization Mediated by Rhodacyclopentadiene

An Unexpected Isomerization In their Communication on page 16442 ff., H. Chen, X. Zhu, and co‐workers investigate controllable stereochemistry in the RhIII‐catalyzed synthesis of benzo[k]fluoranthenes. The experimental results, combined with theoretical mechanism investigations, suggest that E/Z isomerization occurs for substrates bearing electron‐withdrawing groups (EWG; EDG=electron‐donating groups) and that the reaction is mediated by rhodacyclopentadienes. This CC isomerization, controlled by the electronic properties of the substituents, was demonstrated for the first time in transition‐metal‐catalyzed annulation reactions. This work unravels the importance of locked rhodacycles on the stereochemical specificity of RhIII‐catalyzed annulation reactions.