Escape from Palladium: Nickel-Catalyzed Catellani Annulation
Jingfeng Huo, Yue Fu, Melody J. Tang, Peng Liu, Guangbin Dong
Abstract
While Catellani reactions have become increasingly important for arene functionalizations, they have been solely catalyzed by palladium. Here we report the first nickel-catalyzed Catellani-type annulation of aryl triflates and chlorides to form various benzocyclobutene-fused norbornanes in high efficiency. Mechanistic studies reveal a surprising outer-sphere concerted metalation/deprotonation pathway during the formation of the nickelacycle, as well as the essential roles of the base and the triflate anion. The reaction shows a broad functional group tolerance and enhanced regioselectivity compared to the corresponding palladium catalysis.
Topics & Concepts
ChemistryPalladiumAnnulationMetalationRegioselectivityCatalysisTrifluoromethanesulfonateArylNickelBenzocyclobuteneDeprotonationCombinatorial chemistryMedicinal chemistryOrganic chemistryIonAlkylPolymerCatalytic C–H Functionalization MethodsCatalytic Cross-Coupling ReactionsAsymmetric Hydrogenation and Catalysis