The design of complex molecular architectures has evolved considerably thanks to transition metal catalyzed functionalization of C-H bonds.  The half-sandwich cyclopentadienyl (Cp) metal complexes of the group 9  are precious catalysts for the development of challenging transformations. Our group pioneered the development of highly efficient chiral Cp ligands for catalysis.^[1] Their potential was demonstrated in combination with various metals for a variety of enantioselective reactions.^[2] Herein, we present a detailed analysis of under-explored biaryl Cp^x ligands, obtained from concise syntheses. Upon complexation to group 9 metals, the catalysts were characterized by X-Ray analysis and their performances were explored towards benchmark C-H activation transformations.^[3]

In a second part, we report the application of Cp^xRh complexes to enantioselective and diastereoselective cyclopropanation via activation of vinyl C-H bonds.  Combined with the one-step Au(I)-catalyzed formation of the N-enoxyimides substrates from alkynes, the synthetic utility of this method is demonstrated by concise syntheses of KMO inhibitor UPF-648 and members of the oxylipin family of natural products.^[4]

[1] B. Ye, N. Cramer Science 2012, 338, 504.
[2] C. G. Newton, D. Kossler, N. Cramer, J. Am. Chem. Soc. 2016, 138, 3935.
[3] C. Duchemin, G. Smith, N. Cramer, Manuscript submitted.
[4] (a) C. Duchemin, N. Cramer, Org. Chem. Front. 2019, 6, 209-212; (b) C. Duchemin, N. Cramer, Chem. Sci., 2019,10, 2773-2777.