The preparation of
ferrocenes with both axial and planar chiralities
poses a considerable challenge. Herein, we report a strategy for the
construction of both axial and planar chiralities in a ferrocene system
via palladium/chiral norbornene (Pd/NBE*) cooperative catalysis. In
this domino reaction, the first established axial chirality is dictated
by Pd/NBE* cooperative catalysis, while the latter planar chirality
is controlled by the preinstalled axial chirality through a unique
axial-to-planar diastereoinduction process. This method exploits readily
available ortho-ferrocene-tethered aryl iodides (16
examples) and the bulky 2,6-disubstituted aryl bromides (14 examples)
as the starting materials. Five- to seven-membered benzo-fused ferrocenes
with both axial and planar chiralities (32 examples) are obtained
in one step with constantly high enantioselectivities (>99% e.e.) and diastereoselectivities (>19:1 d.r.).
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