Chiral cyclopentadienyl iridium(III) complexes promote enantioselective cycloisomerizations giving fused cyclopropanes.Angew Chem Int Ed Engl. 2015 Oct 05; 54(41):12149-52.AC
The cyclopentadienyl (Cp) group is a very important ligand for many transition-metal complexes which have been applied in catalysis. The availability of chiral cyclopentadienyl ligands (Cp(x)) lags behind other ligand classes, thus hampering the investigation of enantioselective processes. We report a library of chiral Cp(x) Ir(III) complexes equipped with an atropchiral Cp scaffold. A robust complexation procedure reliably provides Cp(x) Ir(III) complexes with tunable counterions. In a proof-of-concept application, the iodide-bearing members are shown to be highly selective for enyne cycloisomerization reactions. The dehydropiperidine-fused cyclopropane products are formed in good yields and enantioselectivities.