Mild complexation protocol for chiral CpRh and Ir complexes suitable for catalysis.

A practical complexation method for chiral cyclopentadienyl (Cp) iridium and rhodium complexes is described. The procedure uses the free CpH with stable and commercially available rhodium(i) and iridium(i) salts without base or additive. The conditions are mild and do not require the exclusion of air and moisture. A salient feature is the suitability for complexations enhancing the user-friendliness of Cp ligands in asymmetric catalysis. DFT-calculations confirm an intramolecular proton abstraction pathway by either the bound acetate or methoxide. Furthermore, the superior facial selectivity of the proton abstraction step enabled the development of TMS-containing trisubstituted Cp ligands which display improved enantioselectivities for the benchmarking dihydroisoquinolone synthesis.