Chapter 1 describes the synthesis of four caltrop-shaped molecules that might be useful as surface-bound electrical field driven molecular motors. The caltrops have a pair of electron donor-accepter arms which form a strong dipole moment. The direction and movement of the dipolar unit could be influenced by an outer electric field. The caltrops also have three benzylic thiols for bonding to a gold surface. Ellipsometry results indicate that monolayers of caltrop molecules form on a gold surface. Chapter 2 and Chapter 3 detail efforts to synthesize libraries of oligo (phenylene vinylene)s (OPVs) using combinatorial synthesis. A series of building blocks for OPVs were synthesized. Model studies were carried out to optimize the reaction strategies and to make OPV tetramers from the building blocks. Chapter 2 describes using the fluorous mixture synthesis (FMS) technology to synthesize a library of OPVs in solution phase. Chapter 3 describes the synthesis of OPVs using solid phase organic synthesis (SPOS). The NMR spectral properties of a group of intermediates frequently encountered in combinatorial synthesis, 1-aryl-3,3-dialkyltriazenes are discussed in Chapter 4.

Research directed toward the design, synthesis, and screening of binaphthyl ketones for catalytic asymmetric epoxidation of alkenes is reported. To date, an easily accessible and recyclable catalyst that tolerates a wide structural variety of unfunctionalized alkenes has not been developed. It has been discovered that fluorinated chiral binaphthyl ketones catalyze the asymmetric epoxidation of alkenes with a high degree of enantiocontrol. A series of five binaphthyl ketone catalysts with variable distribution of fluorine atoms alpha to the carbonyl were synthesized. These catalysts were screened in the asymmetric epoxidation of trans-beta-methyl styrene. A trend of epoxidation efficiency as a function of alpha fluorination was revealed. Although, several of these catalysts performed well in the screening process, the most accessible was an alpha-fluorinated binaphthyl ketone. This ketone epoxidized trans-beta-methylstyrene to trans-beta-methylstyrene oxide with 57% conversion in 80% enantioselectivity. In order to improve conversion and enantioselectivity with this catalyst, a study of the various reaction parameters such as pH, organic cosolvent, and the amount of primary oxidant used was undertaken. During this study a significant dependence on these parameters was revealed, particularly, that of the organic cosolvent. Optimization of these conditions has led to dramatic improvements in the epoxidation efficiency of alpha-fluorinated binaphthyl ketone. This efficiency is highlighted in the epoxidation of trans -beta-methylstyrene to trans-beta-methylstyrene oxide with 100% conversion and 94% ee (from 57% conversion and 80% ee). Moreover, a substrate study suggests the optimized solvent allows for a pi-stack interaction which contributes to high enantioselectivity and conversions for both 1,1-disubstituted and terminal alkenes.

New oligomers, intended for use as potential molecular electronics devices have been synthesized based on rational design principles. A large number of chemically and conformationally diverse molecules have been synthesized, in order to manipulate two physical characteristics of the oligomer: the molecular junction with the bulk phase material, and the molecular electronic behavior due to the conformational and electronic nature of the molecular backbone. For the former characteristic, the new oligomers contained various substrate linkers or "alligator clips", such as thioacetyl and free thiols, isonitriles, nitriles, pyridines groups, as well as diazonium salts for direct substrate attachment. For the latter characteristic, different molecular geometries were synthesized that contained electron-withdrawing groups such as fluorine atoms and nitro groups. These variations are meant to address redox processes, electron-localization and conformational restrictions of the conjugated oligomer, features that are thought to play active roles in the electrical responses of molecular electronic devices. The direct reaction of arenediazonium salts with the solid bulk phase allowed us to extend the molecular electronics field toward the preparation, characterization and use of organically grafted materials that are technologically important such as silicon and gallium arsenide semiconductors, palladium metallic surfaces and individual single-walled carbon nanotubes. The goals of this work include higher current densities, lower conductivity barriers and improved matching between molecular orbitals and the Fermi level from the bulk phase. Finally, through the synthetic work presented here, the importance of a complete and systematic analytical elucidation of the chemisorbed organic films made with these novel oligomers is emphasized, so that the quality and integrity of the chemical interface is better understood before the molecules are assigned as active elements in molecular electronic devices.

Research toward the total synthesis of the promising antibiotic lactonamycin is reported. Lactonamycin exhibits a wide range of potentially useful biological activities. Most notable among these, is the potent activity displayed against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The first reported synthesis of the ABCD-ring system of lactonamycin has been accomplished in nine steps in 15.3% overall yield utilizing a novel tandem cyanide conjugate addition/Dieckmann condensation as the key step. This powerful annulation reaction was developed in a model system prior to application to the synthesis of the ABCD-rings of lactonamycin. Flexibility was observed in the nucleophile used to initiate the cyclization, holding promise for application to the related polyketides tetracenomycin C, elloramycin, saintopin, saintopin E, and tetracenomycin A2. Model studies on the highly oxygenated DEF-ring system were conducted. A high-yielding, regioselective dipolar cycloaddition of a hydroxymethyl-substituted naphthoquinone with an appropriately substituted nitrile oxide was developed, providing rapid entry to an isoxazole intermediate possessing virtually all of the atoms necessary for the DEF-rings of lactonamycin. Diastereoselective installation of a final tertiary hydroxyl remained after [3+2] cycloaddition. Several methods geared toward solving this challenging synthetic problem are presented. In the course of studies on the ABCD-ring system, a methodology for the clay-catalyzed deprotection of acetal-type phenolic ethers was developed. This method proved selective for phenolic acetal-type ethers with an ortho heteroatom, prompting the proposal of a mechanism involving chelation-controlled selectivity.

Luzopeptins are a series of cyclic depsipeptides which possesses potent antitumor and antiviral activities. There is no total synthesis of Luzopeptins has been achieved. In our own effort to synthesize the luzopeptins, we developed a concise and practical route to PCA, 86, and an efficient protocol to synthesize the mono-BOC, 181. A novel serinyl chloride was devised in conjunction with the formation of PCA-serine dipeptide derivatives, 164. All these methodologies were successfully applied to the synthesis of monomeric derivative of luzopeptin E$\sb2,$ 288.* ftn*Please refer to the dissertation for diagram.

The (2.2) paracyclophane-annelated cycloproparenes 1 and 2 were prepared by treating the Diels-Alder adducts of 1-bromo-chlorocyclopropene and either 1-vinyl (2.2) paracyclophane-1-ene (3) or 1,2-dimethylene (2.2) paracyclophane (4) with potassium t-butoxide in THF. Using the same approach the new cycloproparenes 5 and 6 were obtained from the (2.2) paracyclophanetetraenes 7 and 8.* The silver-ion catalyzed polymerization of the dicycloproparenes 9 and 10 was also studied. This method has shown to be an alternative to the repetitive Diels-Alder reaction in the synthesis of ladder polymers. The ladder polymers 11 and 12 were obtained and characterized by IR, solid-state $\sp{13}$C-NMR and thermogravimetric analysis (TGA).* ftn*Please refer to the dissertation for diagrams.

Several fully conjugated organic molecules incorporating 2,7-difunctionalized pyrenes, 2,7-difunctionalized phenanthrenes, 2,5-difunctionalized pyrimidines and 5-functionalized pyrimidines have been synthesized. These molecules all feature a protected thiophenol terminus which under suitable deprotection conditions liberates the free thiol permitting for their self-assembly in the presence of a clean gold surface. This thesis features an improved synthesis of 2,7-dibromopyrene via an optimized hydrogenation/nitration/separation procedure. In addition, a novel route to 2,7-dibromophenanthrene is presented which begins with an easy bromination of diphenic acid and culminates in a hydrazine-induced cyclization of the corresponding 2,2'-dicarbaldehyde to give the desired product dibromophenanthrene in high yield. The completed device syntheses feature various palladium-catalyzed coupling methods to afford the appropriate arylene-ethynlene systems and these will be presented.

Based on rational design principles, diverse arrays of small organic oligomers containing unique electronics structures and redox functionalities have been synthesized for use in molecular-scale electronic device architectures. Thiol terminated oligoanilines were found to exhibit reproducible bistable switching behavior with an on-off ratio of > 10:1 at room temperature when biased between metal electrodes. The synthesis of orthogonally functionalized oligomers has resulted in compounds containing functionalities on one end known to form ordered self-assembled monolayers on metal surfaces while at the other end an intact thioacetate is present whereby self-assembly may again occur after an in situ deprotection for use in NanoCell electronic memories. The NanoCell devices were found to exhibit switching behavior when biased, with a two state memory; however the switching proved to be metallic in nature. Additionally, orthogonally functionalized oligomers allow for the covalent attachment of carbon nanotubes to silicon surfaces for possible uses in sensor and electronic device embodiments. This technique relies on the ability to graft aryldiazonium salts onto a silicon hydride passivated surface followed by diazotization of the terminal aniline. Organic aryltriazenes have been shown to assemble on hydride passivated silicon surfaces by using an in situ diazotization protocol in dilute HF solution. Film thicknesses range from a monolayer to 200 nm depending on conditions. Novel U-shape oligomers have been synthesized to aid in the elucidation of molecular switching behavior and monolayer film formation using advanced surface characterization techniques. These conformationally restricted oligomers are designed to be of use in studies utilizing scanning probe microscopy techniques to elucidate switching mechanisms and negative differential resistance behavior thought to be based on molecular conformational changes.

A synthetic route via chiral precursor 74* had led to a total synthesis of (+)-cyanocycline A. This optically pure synthesis unequivocally determined the absolute stereochemistry of natural cyanocycline A as 2, in contrast to a previously reported X-ray crystallographic assignment as presented on 2$\prime$. ftn*Please refer to dissertation for diagrams.

A new method for the synthesis of N1-(beta- D-2'-deoxyribosyl)-5-methyl-2-pyrimidinone ( 1) was developed. Fluorescent nucleoside 1 was synthesized from thymidine in 5 steps and 40% overall yield. The 3-O-phosphoramidite of 1 was synthesized and oligodeoxyribonucleotides (ODNs) containing 1 were prepared in good yields using standard, automated solid-phase methodology. The ODNs were purified by RP-HPLC or PAGE. The purity of ODNs was analyzed by CE. Fluorescence spectra of the ODNs were recorded. The fluorescence of 1 was substantially quenched when 1 was incorporated into ODNs, and was quenched further after the formation of a double-stranded DNA. The binding of RecA protein to an ODN containing 1 resulted in an increase in the emission fluorescence yield in the absence or in the presence of ATPgammaS. The fluorescence emission and anisotropy changes that accompany the formation of the complexes have enabled us to establish by titration that RecA protein binds to about 3 nucleotides of ODN.