| The first part of this dissertation describes the applications of the copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and terminal acetylenes in the synthesis and functionalization of dendritic materials.; In Chapter 1, an efficient route to build polytriazole dendrimers is described. The resulting dendrimers contain a wide variety of peripheral functional groups, repeat units, and cores, giving high purity and higher yields than have been achieved before.; In Chapter 2, a novel strategy based on the copper(I)-catalyzed triazole reaction for the functionalization of dendrimers is described. The selectivity of the cycloaddition, coupled with mild reaction conditions, permits unprecedented functional group tolerance during the derivatization of dendrimeric and hyperbranched scaffolds. The resulting dendritic libraries are structurally diverse, encompassing a variety of dendritic backbones and surface functional groups, and are prepared in near quantitative yields under very mild conditions.; Chapter 3 describes the synthesis of diblock amphiphilic dendritic polyesters, in which two hybrids were coupled via the copper(I)-catalyzed triazole formation. The application of the resulting segmented macromolecules as bacterial detection tools is also discussed.; Chapter 4 discusses the preliminary results of layer-by-layer deposition on silicon surfaces using azide and acetylene tailored dendrimers.; The second part of this dissertation describes the discovery of highly-reliable and selective reactions that can be carried out in aqueous solutions. Chapter 5 discusses the development of a one-pot procedure for the synthesis of 1,4-disubstituted [1,2,3]-triazoles from activated halides based on the copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and terminal acetylenes.; Chapter 6 discusses the extension of the copper catalysis to the one-pot synthesis of 3,5-disubstituted isoxazoles. The need for isolation and handling of small, potentially explosive organic azides, as well as unstable nitrite oxides, is avoided. These two processes perform best in aqueous cosolvent systems and are tolerant to most functional groups.; Chapter 7 discusses the development of new chiral ligands, which give excellent catalytic turnover (100--500) and moderate to good enantioselectivity in the osmium(VIII)-catalyzed oxidation of olefins. Significantly lower loading of the osmium catalyst was realized (0.2--1 mol% as opposed to 4 mol% with the old procedure) and no diol by-products were detected in the aminohydroxylation reactions. |
