Chiral Cyclopentadienyl Ligands: Design, Syntheses, and Applications in Asymmetric Catalysis.

The creation of new chiral ligands capable of providing high stereocontrol in metal-catalyzed reactions is crucial in modern organic synthesis. The production of bioactive molecules as single enantiomers is increasingly required, and asymmetric catalysis with metal complexes constitutes one of the most efficient synthetic strategies to access optically active compounds. Herein we offer a historical overview on the development of chiral derivatives of the ubiquitous cyclopentadienyl ligand (CpX ), and detail their successful application in a broad range of metal-catalyzed transformations. Those include the functionalization of challenging C-H bonds and beyond, giving access to an extensive catalogue of valuable chiral molecules. A critical comparison of the existing ligand families, their design, synthesis, and complexation to different metals is also provided. In addition, future research directions are discussed to further enhance the performance and application of CpX ligands in enantioselective catalysis.

Rhodium(III)-Catalyzed Cyclopropane C-H/C-C Activation Sequence Provides Diastereoselective Access to α-Alkoxylated γ-Lactams.

A Cp*Rh(III)-catalyzed C-H/C-C bond activation sequence of cyclopropyl hydroxamates has been developed. The three-component process allows trapping of the intermediate rhodacycle with diazomalonates and an alcohol nucleophile to provide access to synthetically valuable α-alkoxylated γ-lactams with trans diastereoselectivity.