Kinetic resolution of planar chiral metallocenes using Rh-catalysed enantioselective C-H arylation

Planar chiral metallocenes have found application in the fields of asymmetric catalysis, medicinal chemistry and materials science. Asymmetric C-H functionalisation provides an efficient synthetic route to substituted chiral metallocenes. However, these methods are often limited by the metallocene substitution patterns they can access. Here, we report a Rh-catalysed asymmetric C-H arylation of 1,2-disubstituted and 1,3-disubstituted pyridyl ferrocenes. Pre-installation of substituents at either the 2- or 3-position of the pyridyl ferrocenes enables this kinetic resolution process to provide access to enantio-enriched 1,2-disubstituted and 1,3-disubstituted metallocenes, and their corresponding C-H arylated products, in excellent enantioselectivity, with selectivity factor values up to 618. This process is able to tolerate a broad range of pre-installed functional groups, such as alkyl, alkenyl, aryl, silyl, thio and fluoro, as well as substitution on the 1 '-cyclopentadienyl ring. The utility of the process has been shown through synthesis and examination of chiral ferrocene ligands. Asymmetric C-H functionalisation provides efficient synthetic routes to chiral metallocenes; however, these methods are often limited by the substitution patterns that can be accessed. Now, a Rh-catalysed enantioselective C-H arylation provides access to chiral 1,2-disubstituted and 1,3-disubstituted metallocenes via kinetic resolution of pre-functionalised metallocenes.