Cyclic (alkyl)(amino)carbene (CAAC) metal complexes can also engage in asymmetric transformations, thereby expanding the toolbox of available chiral carbene ligands.

Well-defined optically pure Transition Metal-complexes bearing C1-and C2-symmetric N-Heterocyclic Carbene (NHC) ligands were prepared from prochiral NHC precursors. As predicted by DFT calculations, our strategy capitalizes on the formation of a metal-carbene bond which induces an axis of chirality. Configurationally stable atropisomers of various NHC containing TM-complexes were isolated by preparative HPLC on a chiral stationary phase in good yields and excellent optical purities (up to 99.5% ee). The carbene transfer from an optically pure Cu-complex to gold or palladium center reveals, for the first time, a full stereoretentivity, supporting the hypothesis of an associative mechanism for the transmetalation. The potential of these new chiral TM-complexes was illustrated in asymmetric catalysis with up to 98% ee.