Design, Synthesis, and Utilization of Iridium(III) Bis(oxazolinyl)phenyl and Iridium(III) Bis(imidazolinyl)phenyl Complexes for Catalytic Enantioselective Atom Transfer C-H Functionalization

The science of organic chemistry has experienced significant advances in recent years due to the increase in efficient methodologies for the synthesis of complex molecules. Traditional synthetic methods have relied on functional groups for selective reactions to be achieved, but these functional groups often require independent preparation and may not be present in the target molecule. Thus, the consideration of carbon-hydrogen (C-H) bonds as functional groups represents a direct approach for overcoming this inherent limitation. C-H bonds were once perceived as being inert, but recent progression of technologies for their functionalization has allowed chemists to incorporate them in synthetic strategies. One such technology involves the design of transition metal complexes that generate a reactive metallocarbene or metallonitrene, which then selectively engages the desired C-H bond to be functionalized and forges a new C-C or C-N bond, respectively. Dirhodium(II) complexes have emerged as state of the art catalysts in metallocarbene and metallonitrene chemistry, but recent reports have revealed that iridium complexes offer reactivity which is unattainable under dirhodium catalysis. Our laboratory discovered that iridium(III) bis(oxazolinyl)phenyl complexes perform catalytic and highly chemo-, regio-, and enantioselective C-H insertion into cyclic dienes using donor/acceptor metallocarbenes. Further catalyst design has led to new iridium(III) bis(imidazolinyl)phenyl complexes which catalyze chemo- and enantioselective C-H functionalization of cyclic ethers using acceptor-only metallocarbenes. Computational analysis of the reactive intermediates has provided substantial insight into the controlling factors for the observed selectivity. Detailed analyses of our efforts to advance the technologies for C-H functionalization through catalyst design are described in this dissertation.