Chiral Bicyclo[2.2.2]octane-Fused CpRh Complexes: Synthesis and Potential Use in Asymmetric C-H Activation

A new class of chiral cyclopentadienyl rhodium(I) complexes (CpRhI) bearing C-2-symmetric chiral bridged-ring-fused Cp ligands was prepared. The complexes were successfully applied to the asymmetric C-H activation reaction ofN-methoxybenzamides with quinones, affording a series of chiral hydrophenanthridinones in up to 82 % yield with up to 99 %ee. Interestingly, structure analysis reveals that the side wall of the optimal chiral CpRh(I)catalyst is vertically more extended, horizontally less extended, and closer to the metal center in comparison with the classic binaphthyl and spirobiindanyl CpRh(I)complexes, and may thus account for its superior catalytic performance.