The natural product celastrol (1) possesses a wide array of promising biological activities related to diseases characterized by protein misfolding including those associated with neuronal degradation, inflammation, and cancer. Relevant to cancer, celastrol functions as a non-ATP-competitive inhibitor of heat shock protein-90, providing a potential lead for the development of new inhibitors with improved pharmacology. A laboratory preparation of the small molecule was undertaken to provide access to the unnatural enantiomer of celastrol. The lack of understanding of the chemistry and biology of the growing class of celastroids is attributed to the incompatibility of biologically inspired polyene cyclization strategies to assemble friedelin triterpenoids. As a result of these problems residing at the interface of chemistry and biology, a purely synthesis-based strategy for polyene cyclizations to rapidly construct the pentacyclic core of the friedelin and celastroid natural products has been developed. This efficient strategy is gram scalable culminating in the first total synthesis of wilforic acid (127) and an advanced intermediate capable of delivering celastrol (1) as well as numerous celastroid natural products. Phenols possess broad utility serving as key materials in all facets of chemical industries, especially the pharmaceutical industry. The ideal synthesis of a phenolic compound entails the direct oxidation of an aryl C-H bond remains to be a difficult synthetic challenge. Following our initial report describing the hydroxylation of arenes using phthaloyl peroxide, new peroxide derivatives were investigated to probe their reactivity in an effort to hydroxylate aromatics which were previously unreactive. Electronically poor to moderately rich arenes were successfully hydroxylated with a broad functional group tolerance using 4,5-dichlorophthaloyl peroxide. This protocol has been applied toward the rapid synthesis of phenolic analogs and metabolites of current pharmaceuticals as well as biocides. Mechanistic studies using kinetic isotope effect, competition, and benzylic oxidation experiments indicate that a novel diradical reverse-rebound mechanism is the likely pathway. Further examination of the transition-state using linear free energy relationships with sigma vs. sigma+ values established a linear trend with a low negative rho value (- 3.92) corresponding best using sigma values supporting a diradical reverse-rebound addition. / text

xxi, 172 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Main group supramolecular chemistry is a rapidly expanding field that combines the tools of coordination chemistry with the unusual and frequently unexpected coordination preferences exhibited by the main group elements. Application of established supramolecular design principles to those elements provides access to novel structure types and the possibility of new functionality introduced by the rich chemistry of the main group. Chapter I is a general review of the field of main group supramolecular chemistry, focusing in particular on the aspects of coordination chemistry and rational design strategies that have been thus far used to prepare polynuclear "metal"-ligand assemblies. Chapter II is a discussion of work toward supramolecular assemblies based on the coordination preferences of lead(II), in particular focusing on the 2-mercaptoacetamide and arylthiolate functionalities to target four-coordinate and three-coordinate geometries, respectively. Several possible avenues for further pursuing this research are suggested, with designs for ligands that may provide a more fruitful approach to the coordination of lead(II). Chapter III deals with the preparation of As 2 L 3 assemblies based on flexible ligand scaffolds. These assemblies exhibit structural changes in response to temperature and solvent, which may provide some insight into the subtle shape requirements involved in supramolecular guest binding. Chapter IV continues this work with an examination of how ligand structure affects mechanical coupling of stereochemistry between metal centers when the chelate ring is completed by a secondary bonding interaction such as the As-π contact. Finally, Chapter V presents a crystallographic and synthetic study of the nature of the interaction between pnictogens and arene rings. This interaction is ubiquitous in the coordination chemistry performed in the Johnson laboratory; understanding the role these interactions play in determining the final structure of supramolecular assemblies is vital to the preparation of more complex structures. Chapter VI presents a set of conclusions and outlook for future work on lead(II) supramolecular assemblies and the dynamic assemblies prepared from flexible organic scaffolds. This dissertation contains previously published and coauthored material. / Committee in charge: Kenneth Doxsee, Chairperson, Chemistry; Darren Johnson, Advisor, Chemistry; David Tyler, Member, Chemistry; Victoria DeRose, Member, Chemistry; Stephen Remington, Outside Member, Physics

<p> Affinity capillary electrophoresis (ACE) is a versatile technique for assessing non-covalent molecular interactions in free solution provided that there are significant changes in apparent analyte mobility as a result of specific complexation. The thermodynamics of receptor binding are vital for controlling the selectivity in molecular recognition, which are dependent on the electrolyte composition of solution. In addition, the conformational properties of the complex (e.g., size, shape) can also contribute a secondary influence on receptor selectivity that has been relatively unexplored in ACE to date. In this study, dynamic 1:1 host-guest inclusion complexation involving a anionic resorcin[4]arene with a group of neutral corticosteroids was examined by ACE, where the macrocycle serves as both an intrinsic buffer and electrokinetic host. The tetraethylsulphonate derivative of 2-methylresorcin[4]arene (TESMR) was first synthesized via an acid-catalyzed condensation reaction, which was then fully characterized in terms of its weak acidity (pKa), mobility, UV spectral and buffer capacity properties. TESMR solutions were demonstrated to have stable intrinsic buffer and ion transport properties at pH 7.5 even at low ionic strength. It was determined that over a 200 % enhancement in the apparent binding constant (KB) was realized by ACE when using TESMR as an intrinsic buffer at pH 7.5 relative to an extrinsic sodium phosphate buffer system, which was also confirmed by 1H-NMR. The coupling of thermodynamic (KB) and electrokinetic (μep, AC) factors associated with complex formation in buffered aqueous solutions that minimize the effects of extrinsic electrolytes serves to enhance enthalpy-driven molecular recognition processes by ACE.</p> / Thesis / Master of Science (MSc)

This dissertation describes the design and synthesis of a series of half-sandwich amino acid complexes of the form), (aa = α-amino carboxylate), and their utility as asymmetric transfer hydrogenation catalysts of ketones. Variation of the metal center, the n-ring, and the aa was used to tune these systems for specific sets of ketones. Upon reaction with homochiral]s, the ligand environment in all of these complexes is pseudotetrahedral, leading to stereogenic metal ions (SM, RM). The addition of another stereogenic center from the amino acid ligand (the carbon, RC or SC;glycine) gives rise to two pairs of diastereomeric complexes. / Ph. D.

Yes / The complexes [RuCp*(PP)Cl] (Cp* = C5Me5; [1], PP = dppm; [4], PP = Xantphos), [RuCp#(PP)Cl] (Cp# = C5Me4(CH2)5OH; [2], PP = dppm; [5], PP = Xantphos) and [RuCp*(dppm)(CH3CN)][SbF6] [3] were synthesized and evaluated in vitro as anticancer agents. Compounds 1–3 gave nanomolar IC50 values against normoxic A2780 and HT-29 cell lines, and were also tested against hypoxic HT-29 cells, maintaining their high activity. Complex 3 yielded an IC50 value of 0.55 ± 0.03 μM under a 0.1% O2 concentration.

Yes / The association of the arene ruthenium metallacycle [Ru4(p-cymene)4(bpe)2(donq)2][DOS]4 (bpe = 1,2-bis(4-pyridyl)ethylene, donq = 5,8-dioxydo-1,4-naphtoquinonato, DOS = dodecyl sulfate) with pyrenyl-functionalized poly(arylester) dendrimers bearing cyanobiphenyl end-groups is reported. The supramolecular dendritic systems display mesomorphic properties as revealed by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering measurements. The multicomponent nature of the dendrimers and of the corresponding host–guest supramolecules (i.e., end-group mesogens, dendritic core, pyrene unit, aliphatic spacers, and metallacycle) leads to the formation of highly segregated mesophases with a complex multilayered structure due to the tendency of the various constitutive building-blocks to separate in different organized zones. The pyrenyl dendrimers exhibit a multilayered smectic A-like phase, thereafter referred to as LamSmA phase to emphasize this unaccustomed morphology. As for the corresponding Ru4–metallacycle adducts, they self-organize into a multicontinuous thermotropic cubic phase with the Im3̅m space group symmetry. This represents a unique example of liquid-crystalline behavior observed for such large and complex supramolecular host–guest assemblies. Models of their supramolecular organizations within both mesophases are proposed. / R.D. thanks the Swiss National Science Foundation (Grant No 200020-140298) for financial support.

Yes / The synthesis of nanoparticles of conjugates of caffeic acid-modified chitosan with ruthenium arene complexes is described. The chemical structure and physical properties of the nanoparticles were characterised by electronic absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and circular dichroism (CD) analysis. The multi-spectral results revealed that caffeic acid is covalently bound to chitosan and chelates to {Ru(p-cymene)Cl}+. The DLS studies indicated that the Ru–caffeic acid modified chitosan nanoparticles are well-defined and of nanometre size. Such well-defined nanocomposites of chitosan and metal complexes might find a range of applications, for example in drug delivery. / We thank the National Natural Science Foundation of China (Project No. 21571154), the Jiangsu Overseas Research & Training Program for University Prominent Young & Middle-aged Teachers and Presidents, Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), the ERC (Grant No. 247450 to PJS), EPSRC (EP/F034210/1 to PJS) and Science City (AWM/ERDF) for support, and EU COST Action CM1105 for stimulating discussions.

Voir fichier joint.

Cette thèse présente la synthèse de ligands originaux construits sur des plateformes coniques de type résorcin[4]arène ou calix[4]arène étant susceptibles de positionner un métal à proximité d'une unité réceptrice: a) des bis-binaphtylphosphites optiquement actifs dont les centres phosphorés ont été greffés sur le bord supérieur de cavités génériques. Ces coordinats ont été testés en hydroformylation asymétrique d’arènes vinyliques et ont conduit à une sélectivité iso très élevée avec de bons, voire très bons excès énantiomériques; b) des carbènes N- hétérocycliques ayant soit un, soit les deux atomes d'azote substitués par des unités résorcinarényle (variante cavitand) et leur utilisation pour la formation d'espèces comportant un centre métallique supramoléculairement piégé dans la partie cavitaire (complexes du type [NiXCpL] (X = Br ou Cl, Cp = cyclopentadiényle, LH = NHC). Ces complexes se sont avérés efficaces en dimérisation de l'éthylène; c) des carbènes N-hétérocyliques anormaux obtenus à partir de sels de triazolium comportant un ou deux substituants résorcinarène. Ces composés à fort encombrement ont été efficacement employés en couplage croisé de Suzuki-Miyaura entre des chlorures d'aryles volumineux et des acides arylboroniques stériquement encombrés. Les activités les plus importantes ont été obtenues avec le sel de triazolium stériquement le moins encombré, celui portant un seul substituant résorcinarène. Sa plus grande efficacité est due à une approche plus facile des substrats dans les intermédiaires catalytiques correspondants ainsi que de la présence de groupes pentyles flexibles pouvant interagir stériquement avec le centre métallique de manière à faciliter l'étape d'élimination réductrice / This thesis describes the synthesis of a series of compounds built on conical resorcin[4]arene and calix[4]arene platforms: a) diphosphites derived from optically active binol, in which the phosphite moieties have been grafted to the wider rim of the generic cones. These ligands were assessed in asymmetric hydroformylation of vinyl arenes and led to high iso selectivity with good to excellent enantiomeric excess; b) N-heterocyclic carbenes bearing either one or two cavitand moieties and their use for the synthesis of [NiXCpL] complexes (X = Br or Cl, Cp = cyclopentadienyl, LH = NHC) in which the NiCp moiety has been supramolecularly trapped in a resorcinarene bowl. These complexes were found active in ethylene dimerization; c) bulky triazolium salts with one or two resorcinarene substituents that were found suitable for the synthesis of complexes with abnormal NHCs. The latter were tested in palladium-catalysed Suzuki-Miyaura cross-coupling of bulky aryl chlorides with sterically hindered aryl boronic acids. Better activities were observed with the sterically less hindered triazolium salt, which bears a single resorcinarene substituent. Its higher efficiency arises from a higher substrate accessibility in the resulting catalytic intermediates as well as the presence of flexible pentyl groups that may interact with the metal centre so as to facilitate the reductive elimination step.

This thesis sought to expand upon the synthetic application of the underexploited ipso, ortho diene cis-diol microbial arene oxidation product from benzoic acid. The microbial oxidation of benzoic acid by mutant strains of bacteria to give the ipso, otho diene cis-diol may be considered to be a green and clean method. This biocatalytic route yields large quantities of an enantiopure chiral building block, which is not assessable via traditional synthetic methods. The fermentation product has seen application towards the synthesis of aminocylitols, which have been tested for their biological activity. Attempts to synthesise the fully oxygenated counterparts, cyclitols, were investigated. Expansion of previous work using a bromine substituted derivative led to a range of cross-coupled and iron co-ordinated products. Finally, a range of novel chiral acids and ketones were synthesised and evaluated for their catalytic activity towards asymmetric epoxidation.