A Tunable Class of Chiral Cp Ligands for Enantioselective Rhodium(III)-Catalyzed C–H Allylations of Benzamides

The lack of robust and tunable chiral versions of cyclopentadienyl
(Cp) ligands hampers progress in the development of catalytic asymmetric
versions of a myriad of reactions catalyzed by this ubiquitous ligand.
Herein, we describe of a class of chiral Cp ligands with tunable steric
parameters. Coordinated to transition metals, the ligand creates a
well-defined chiral pocket, able to imprint its chirality onto the
metal. The corresponding Rh complexes are shown to be excellent catalysts
for enantioselective allylation of N-methoxybenzamides
via directed C–H functionalizations at very mild conditions.
The obtained enantioselectivities are excellent and demonstrate the
viability of chiral Cp complexes as selective transition metal catalysts.