The development of ligands for C-H functionalization utilizing amino acid derived directing groups

Abstract

The functionalization of unreactive bonds has become a focus of new reaction methodology. The foremost difficulty lies within achieving high levels of chemo-, regio-, and stereoselectivity without the need for molecular complexity. The aim of my project was to develop a catalyst system that could direct a C-H functionalization by forming a transient covalent attachment to a simple substrate and release the substrate after the transformation. I have developed two asymmetric catalysts for the C-H acetoxylation of sp3 and sp2 bonds. The sp3 C-H acetoxylation occurs with high levels of diastereoselectivity, demonstrating the compatibility of this idea for enantioselective C-H functionalization. In the course of my asymmetric ligand development, I engineered a stereoretentive synthesis for the formation of quaternary asymmetric amino amides. The straightforward synthesis involves facile, high yielding conversion of L-proline into a broad scope of differentially substituted amides with excellent enantioselectivity. Furthermore, my exploration into amino acid derived ligands has uncovered a new method for C-C bond formation. The coupling of aryl substrates, originating from aryl sulfonamides, with olefins in a Heck-type transition metal catalyzed process has been discovered from examining serine scaffolds. This transformation may become a useful addition to the arsenal of C-C bond forming reactions.