Organic Catalysis with Metal-Dinitrosyl Complexes and Synthetic Biomimetic Supramolecular Nanovessels

The work described in this dissertation explores the field of organic catalysis with metal-dinitrosyl complexes and synthetic supramolecular nanovessels. Part I (Chapters 1-3) presents the development of both stoichiometric and catalytic vinylic C-H functionalization reactions of unactivated alkenes mediated by cobalt and ruthenium dinitrosyl complexes. Part II (Chapters 4-7) describes the design and synthesis of terephthalamide-based supramolecular M4L6 nanovessels and their application in organic catalysis./nPart I - Metal-Dinitrosyl Mediated Vinylic C-H Functionalization/nChapter 1 contains a brief literature review of C-H activation and functionalization reactions mediated by transition-metal complexes. Of the examples presented, the cobalt dinitrosyl mediated intermolecular vinylic C-H functionalization reaction offers an approach for the activation of simple alkenyl C-H bonds that takes advantage of the ligand-based reactivity of such cobalt complexes. The difficulties of isolating the reactive cobalt dinitrosyl species and achieving catalytic turnover for functionalization, as well as extension toward other metals, are also presented to provide a context in which Chapters 2 and 3 can be viewed./nChapter 2 describes the development of a one-pot cobalt-dinitrosyl mediated inter- and intramolecular vinylic C-H functionalization reaction of unactivated and alkyl-substituted alkenes. Enantioselective intramolecular cobalt-dinitrosyl mediated 5-exo-trig and 6-endo-trig cyclization reactions are also described. Although catalytic turnovers can be achieved with such complexes for vinylic C-H functionalization, generality of the methodology and broader substrate scope remain elusive./nChapter 3 presents the application of a ruthenium-dinitrosyl complex in the context of vinylic C-H functionalization reaction of simple alkenes. The recently discovered ruthenium-dinitrosyl complex proves to be stable for isolation and characterization, an improvement over the cobalt system, but also proves to be less reactive as a catalyst for vinylic C-H functionalization. The challenges associated with the development of metal-dinitrosyl catalyzed C-H functionalization and its outlook are also discussed./n/nPart II - Synthesis of Terephthalamide-based Ga4L6 Supramolecular Nanovessels and their Application in Enantioselective and Stereospecific Organic Catalysis/nChapter 4 introduces the field of supramolecular chemistry with a main focus on the synthesis and chemistry of enantiopure host complexes. Examples of asymmetric organic reactions catalyzed by chiral host assemblies are also presented to provide a platform from which Chapters 5-7 can be viewed./nChapter 5 describes the design, synthesis and characterization of enantiopure supramolecular Ga4L6 nanovessels that are based on terephthalamide (TAM)-derived ligands. The synthesis of achiral TAM-based ligands and their corresponding racemic host-guest complexes are also presented./nChapter 6 summarizes the development of an enantioselective ring-opening reaction of meso-episulfonium catalyzed by the enantiopure host assembly presented in Chapter 5. Additionally, the application of this new cluster as a chiral host catalyst for the Aza-Cope rearrangement and the Prins-like cyclization reactions are also discussed./nChapter 7 describes the development of a stereospecific reaction catalyzed by both racemic and enantiopure supramolecular Ga4L6 host assemblies. The host assemblies are capable of catalyzing the substitution reaction at a secondary benzylic carbon center to give products with overall stereochemical retention, while reaction of the same substrates in bulk solution gives products with inversion. Such ability of a biomimetic synthetic host assembly to reverse the stereochemical outcome of a nucleophilic substitution reaction is unprecedented in the field of supramolecular catalysis.

Advisor: Bergman, Robert G
Toste, F. Dean