Chiral Cyclopentadienyl Rh(III)-Complexes for Asymmetric C-H Functionalizations

Pentamethylcyclopentadienyl (Cp*) based transition-metal-catalyzed C-H functionalization has become an important synthetic tool for the construction of molecular complexity from simple starting materials. Despite their high potential, the corresponding asymmetric transformations with late transition metal complexes, where the chirality solely stems from the Cp fragment, are completely elusive. We have elaborated facile and flexible syntheses of two tunable classes of enantiopure C2-symmetric Cp ligands as the stereo-controlling elements. The viability of our novel concept to achieve high level of stereoselectivity was proved by four applications on asymmetric Rh(III)-catalyzed C-H functionalizations such as enantioselective synthesis of dihydroquinolones, asymmetric C-H allylations of benzamides, enantioselective hydroarylation to dihydrobenzofurans and asymmetric synthesis of isoindolones. Both classes of chiral CpX*-Rh complexes demonstrate high reactivity, delivering the products with excellent regio- and enantio-control.