Enantioselective Assembly of Ferrocenes with Axial and Planar Chiralities via Palladium/Chiral Norbornene Cooperative Catalysis

The preparation of ferrocenes with both axial and planar chiralities poses a considerable challenge. Herein we report a new strategy for the construction of both axial and planar chiralities in a ferrocene system via palladium/chiral norbornene (Pd/NBE*) cooperative catalysis. In this fascinating domino reaction, the firstly established axial chirality is dictated by Pd/NBE* cooperative catalysis, while the latter planar chirality is controlled by the pre-installed axial chirality through a unique axial-to-planar diastereoinduction process. This method exploits readily available ortho-ferrocene-tethered aryl iodides (14 examples) and the bulky 2,6-disubstituted aryl bromides (14 examples) as the starting materials. 5- to 7-membered benzo-fused ferrocenes with both axial and planar chiralities (29 examples) are obtained in one step with constantly excellent enantioselectivities (> 99% e.e.) and diastereoselectivities (> 19:1 d.r.).