Pentamethylcyclopentadienyl rhodium(III)-chiral disulfonate hybrid catalysis for enantioselective C-H bond functionalization

Though Cp*Rh(III) complexes are prominent and versatile catalysts for C-H bond functionalization reactions, catalytic stereocontrol is difficult due to the lack of vacant coordination sites. Here, we report a hybrid strategy for inducing chirality without using previously reported chiral Cp-x ligands. A preformed hybrid catalyst, [Cp*RhLN][6,6'-Br-(S)-BINSate], catalysed C-H activation and subsequent conjugate addition of 2-phenylpyridine derivatives to enones in good yield and enantioselectivity (enantiomeric ratio up to 95:5). In addition to 2-phenylpyridines, the conjugate addition of 6-arylpurines proceeded with an enantiomeric ratio of up to 91:9 using [Cp*RhLN](R)-SPISate]. The results demonstrate that a chiral organic anion can efficiently control the enantioselectivity of Cp*Rh(III)-catalysed C-H bond functionalization without a chiral Cp-x ligand.