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Thesis advisor: Kian L. Tan / Chapter 1. We reported the first synthesis of all-carbon quaternary centers via hydroformylations using a catalytic directing group. With the ability of reversibly and covalently binding to a substrate, and coordinating to a metal center, scaffolding catalyst 1.1 is able to direct the branch-selective hydroformylation of 1,1-disubstituted olefins under mild temperature. Chapter 2. We have designed and synthesized a chiral organocatalyst 2.11. This catalyst is able to covalently bind to one hydroxyl, and utilize the induced intramolecularity to stereoselectively functionalize the other hydroxyl within a cis-1,2-diol via electrophile transfer. Catalyst 2.11 was used in the desymmetrization of meso-1,2-diols under mild conditions (4 C to room temperature), leading to high yields and selectivities for a broad substrate scope. Chapter 3. Catalyst 3.1 and 3.6 were demonstrated to selectively bind to primary hydroxyls over secondary hydroxyls. By combining the binding selectivity with asymmetric catalysis, these scaffolding catalysts were shown to promote the selective silylation of secondary hydroxyls within terminal (S)-1,2-diols. The reversal of substrate bias was further applied to a regiodivergent kinetic resolution of racemic terminal 1,2-diols, producing secondary protected products in synthetically practical levels of enantioselectivity (>95:5 er) and yields (≥40%). Time course studies of this reaction further revealed the optimal condition to form the primary silylated product in high s-factor. Chapter 4. Based on the previous understanding of catalyst 4.5 and 4.6, the exclusive catalyst recognition of cis-1,2-diols within polyhydroxylated molecules was further discovered. This unique functional group display recognition was further allied with the catalyst's ability to stereoselectively differentiate hydroxyls within cis-1,2-diols, enabling the site-selective protection, functionalization, and activation of the inherently less reactive axial hydroxyl groups within carbohydrates. This methodology also enables the selective functionalization of multiple complex molecules, including digoxin, mupirocin, and ribonucleosides, demonstrating the potential power of scaffolding catalysis in the rapid access to valuable synthetic derivatives of polyhydroxylated compounds. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Investigation on the chemical constituents of the EtOH extract of the soft coral Lobophytum sarcophytoides, collected off the coast of Dongsha Atoll, Taiwan, has led to the isolation of ten natural compounds 1¡V10, including four new cembrane-type diterpenoids, Sarcophytolins A¡VD (1¡V4) and one new polyhydroxylated steroid 23, 24-Dimethyl-cholesta-5, 16-diene-3£], 20£\-diol (5) along with five know compounds 6¡V10¡CThe structure of compounds 1¡V10 were established by detailed spectral data analysis (IR, MS, 1D, 2D NMR) and by comparison of the spectral data with those of the related known compounds. The relative stereochemistries of compound 5 was further confirmed by X-ray single-crystal diffraction analysis. The cytotoxicity of compounds 1¡V10 against the Daoy (human medulloblastoma), Hep-2 (human laryngeal carcinoma), MCF-7 (human breast adenocarcinoma), CCRF-CEM (human T-cell acute lymphoblastic leukemia), and DLD-1/WiDr (human colon adenocarcinoma) tumor cell lines were determined. Compounds 6, 8, 9, and 10 exhibited moderate cytotoxicities against the tested tumor cells. Furthermore, compounds 1, 2, 4, 6, and 10 were found to show significant activity against the accumulation of the pro-inflammatory iNOS protein at 10 £gM.

<p> This thesis describes the isolation and structural determination of flavonoids from the heart wood of Prunus avium as well as synthesis of polyhydroxy pyrrolidine derivatives and aniline core structures as potential antibacterial agents. Nitrogen-synthons containing saturated heterocyclic systems and aniline core structures are important synthons in organic chemistry because of their presence in many biologically-active natural products. Mycobacterial viability is dependent upon the ability of the organism to produce an intact cell wall. Therefore, compounds that interfere with the biosynthesis of the cell wall complex glycons have the potential to become new drugs for the treatment of mycobacterial infections. The oligosaccharide galactan is one of the major structural components of the outer wall of the micro-organism. Galactofuranose is essential for cell growth and survival and therefore, its biosynthesis constitutes a new drug target. The biosynthetic process involves several enzymes having Uridine-diphosphogalacto furanose (UDP-Galf) as the substrate; uridine 5^1 -diphosphogalacto pyranose mutase which catalyzes the interconversion of UDP galacatopyranose to UDP-galactofuranose as well as Galf-transferase. We are seeking and designing molecules that could be mechanistic probes and/or inhibitors of efflux pumps to potentially combat multidrug resistance.</p> <p> The isolation and structure-determination of six naturally occurring Flavan-type Natural products was performed. Such derivatives are known to reverse multiple-drug-resistance (MDR) in persistent microbial infections. The synthesis of pyrrolidine-based antibacterial agents was attempted using two different approaches from tartaric acid. These derivatives were designed as potential transition-state mimics of a carbohydrate processing enzyme specific to TB. A synthetic approach to the aromatic core structure of the antibacterial agent Platensimycin was also investigated. The synergistic use of cytotoxic agents in conjunction with efflux-pump modulators is an emerging area of research in the MDR field; our efforts to make available materials for high-throughput screening in this area will be described.</p> / Thesis / Master of Science (MSc)

Orientador: Carlos Roque Duarte Correia / Acompanha Anexo denominado V.2. Paginação continua / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T12:04:47Z (GMT). No. of bitstreams: 1 Garcia_ArielLazaroLlanes_D.pdf: 15520800 bytes, checksum: 2744757a92f3045d187a1c68320729d5 (MD5) Previous issue date: 2008 / Resumo: A reação de arilação de Heck-Matsuda é um procedimento sintético valioso e extremamente versátil para a formação de ligações carbono-carbono, baseada no acoplamento de uma olefina com um sal de arenodiazônio na presença de uma espécie organometálica de paládio zerovalente. Recentemente, a utilização desta reação tem ganhado espaço na arte de sínteses totais, demonstrando a viabilidade da mesma. Neste trabalho, apresentamos o desenvolvimento de metodologias novas e flexíveis para a síntese eficiente de vários produtos naturais e sintéticos com propriedades farmacológicas importantes, utilizando a reação de arilação de Heck-Matsuda como etapa chave. No total, foram sintetizados 21 compostos finais, incluindo: prolinas e pirrolidinas poliidroxiladas racêmicas e quirais, Radicamina B e outros a-C-ariliminociclitóis quirais análogos das Radicaminas A e B, Rolipram, ácidos b-aril-g-aminobutíricos análogos do Baclofeno, e um precursor chave de Prepolicitrina A e Policitrina A. Os compostos sintetizados, assim como seus respectivos intermediários de reação, foram plenamente caracterizados e os resultados obtidos foram comparados com aqueles reportados na literatura quando aplicável. Dados analíticos e espectroscópicos satisfatórios foram obtidos em todos os casos. / Abstract: The Heck-Matsuda arylation reaction is a valuable and extremely versatile synthetic procedure for carbon-carbon bond formation, based on the coupling of an olefin with an arenediazonium salt in the presence of a zerovalent palladium organometallic specie. Recently, the use of this reaction has been gaining space in total syntheses, demonstrating its viability. In this work, we presented the development of new and flexible methodologies for the efficient synthesis of several natural and synthetic products with important pharmacologic properties, using the Heck-Matsuda arylation reaction as a key stage. Totally, a set of 21 final compounds were synthesized, including: racemic and chiral polyhydroxylated prolines and pyrrolidines, Radicamine B and other chiral C-aryl-iminocyclitols analogues of Radicamines A and B, Rolipram and b-aryl-g-aminobutyric acids analogues of Baclofen, and a key precursor of Prepolycitrin A and Polycitrin A. The synthesized compounds, as well as their respective reaction intermediates, were entirely characterized and the obtained results were compared with those reported in the literature when applicable. Satisfactory analytical and spectral data were obtained in all cases. / Doutorado / Quimica Organica / Doutor em Ciências

Masters of Science / A chemical study on the total extract of the zoanthid Palythoa tuberculosa, collected from the Red Sea, resulted in the isolation of seven polyhydroxylated sterols viz: palysterols A-G, six of which are new. Their chemical structures were elucidated on the basis of their 1D and 2D NMR and MS spectroscopic data. Palysterols B and G demonstrated cytotoxic activity on three human cancer cell lines (MCF-7, HeLa, and HT- 29). Palysterol G, in particular, was able to induce apoptosis in breast adenocarcinoma(MCF-7) cells

Les nitrones peuvent être réduites par le diiodure de samarium et réagir selon une additionconjuguée avec des acrylates-silylés, silylés ou ,disilylés. Ce couplage réducteur,développé avec des aldonitrones simples, a conduit à des dérivés silylés de g-Nhydroxyaminoacides.Ces derniers ont pu être réduits puis cyclisés en g-lactames substituéspar un groupement silylé, dont la position et la configuration dépendent de l’acrylate dedépart. L’oxydation de Tamao-Fleming a ensuite permis la conversion des composés silylésen leurs correspondants hydroxylés avec rétention de configuration. Cet enchaînementréactionnel a alors été appliquée à une nitrone cyclique polyalkoxylée dérivée du L-xylose, cequi a permis les synthèses de la 7-desoxy Uniflorine A et de la (+)-Australine, deuxpyrrolizidines polyhydroxylées inhibiteurs de glucosidases. / Nitrones are reduced by samarium diiodide and react through a conjugated addition with silylacrylates. This cross coupling, developed with simple aldonitrones, allowed the preparation ofsilyl g-N-hydroxyaminoacids derivatives. The latter were reduced and cyclised in g-lactams inwhich the position and the configuration of the silyl group depend of the starting acrylate.Tamao-Fleming oxidation was used for the conversion of silyl group to hydroxyl group withretention of configuration. Then, the reaction was applied to a cyclic polyalkoxy nitronederived from L-xylose and it allowed the synthesis of 7-deoxy Uniflorine A and (+)-Australine, polyhydroxylated pyrrolizidines exhibiting glucosidases inhibition.

(FOR FIGURES REFER THE MAIN PDF FILE) Supramoleculr chemistry, aptly termed by Lehn as the study of molecular sociology, is the chemistry of the intermolecular bond, focusing on the structures and functions of “supermolecules” –chemical system formed by the association between two or more molecular components. While interrelated, this discipline forges beyond the domain of traditional molecular chemistry, which seeks to master the manipulation of the covalent bond between atoms and uncover the principle that governs the structures and properties of molecular species. Supramolecular chemistry assayas to blend the comprehensive resources of molecular chemistry with designed control of the intermolecular interactions to engineers supramolecular with features as well defined as those of the constituent molecular themselves. Not surprisingly, it has been stated that supramoleculars are to molecules and the intermolecular bond what molecules are to atoms and the covalent bond. In the realm of molecular crystals, the focus of supramolecular chemistry and indeed, the scope of the present thesis coverings with that of a rather recent, but rapidly emerging scientific discipline, namely crystal engineering. Coined nearly four decades ago in connection with photodimerization reaction in crystalline cinnamic acids, the term” crystal engineering” has since then broadened its expanse considerably and is, at present, most appropriately defined as“the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding in the design of new solids with desired physical and chemical properties”. It would be befitting to remark that it is very pursuit (and more often than not, the elusive target) of being able to make functional solids by design that has allowed crystal engineering to evolve from an object of mere Scientific curiosity to a subject of tremendous utilization value. No proof for this assertion might be greater than that which lies in the fervent efforts put forth by pharmaceutical companies in understanding and controlling drug polymorphism, especially in the wake of the contemporary legal implications attendant with observing such a phenomenon. Polymorphism in molecular crystals results from the possibility of at least two different arrangements of the molecular of a given compound in the solid state and has therefore often been regarded as the” dark side” of crystal engineering. On one hand, polymorphism presents itself as an important probe in the study of structure-property relationship and allows elucidation of the varied macroscopic properties of the same molecule self-assembled in different crystalline environments. On the other hand, the phenomenon poses an implicit complication when predicating the product of a crystallization process forms the goal of a crystal engineering project. This is particularly true in case of crystal structure prediction (CSP) from the molecular structure of a given compound, where the experimentally obtained polymorphic modification may be a kinetic form and therefore, need not correspond to the one ranked lowest in energy from the computational studies. Indeed, this dichotomy between a thermodynamically and a kinetically controlled crystallization process reflects the underlying uncertainty associated with judging the outcome of a crystallization event. In this concept of a supramolecular synthon has been postulated to assimilate both thermodynamic and kinetic alternative, and therefore provide a working model for heuristic crystal design. By analogy with corey’s definition of a molecular synthon, a supramolecular synhon has been described” a structural unit within a supramolecule which can be formed and/or assembled by known or conceivable synthetic operations involving intermolecular interactions”. Being entirely probabilistic in nature, the robutness and thus, the transferability of a particular synthon to a designed crystal is assessed from a systermatic evolution of its recurrence in crystal structures of representative molecules. The Cambridge Structural Database (CSD), which announced the inclusion of the 500000th crystal structures in its archives last year, provides an invaluable cache of experimentally determined structures and the foundation for crystal design in this regard. The practically of the supramolecular synthon approach, now almost synthymous with crystal engineering, has been demonstrated not only in the successful design of a number of functional solids, but also in its possible application in CSP as a knowledge-based alternative. Irrespective of the approach, a basic paradigm can however be constructed from any crystal engineering strategy, viz. construct the molecular building blocks and assemble these, with a prior knowledge of the possible non-covalent interactions, in a manner that leads to the desired crystal structure. This premise will form the central theme of the present thesis, entitled “From molecular to supramolecular: Probing solid state self –assemblies of conformatonally locked polycyclitos and structural siblings”. The dissertation will deal with the nuances of the self-assemblies of four classes of structurally related crystalline polycyclie compounds, all fashioned from a prototypical rigid trans-decalin backbone derived from commonly available aromatic precursors like naphthalene and anthracene. The thesis will be presented in four chapters, each based on one of the four functional make-ups present in the molecular under study. • Chapter 1.Relating intramolecular O-H…Ohydrogen bondigs to conformational locking: Design and self-assemblies of crystalline polyclitols. • Chapter 2.Preferences of supramolecular assemblies towards competing inter- and intramolecular O-H…O hydrogen bonds: A case study in crystalline acyldervaeives of conformarionally locked polyclitols. •Chapter 3.Synthesis of novel polyhydroxylated flustrates: Probing fluorine interactions in a conformatonally constructed environment. • Chapter 4. Strength vs.accessiblity: Universe the patterns of self-recognition in designer conformationally locked aminoacohols. A brief overview of each chapter is presented below. The first chapter of the thesis investigates the supramolecular chemistry of an O-H…O Hydrogen Bond formed between hydroxyl groups that have been constrained to occupy spatiality invariant position in the crystal structure of a polycyclitol (a portmanteau word derived from polycyclic cyclitol). Having been constructed on a grid trans-decalin carbocyclic backbone, the polycyclitols under study 1-6 are conformatonally locked and destined to exhibit an axial rich disposition of the hydroxyl groups, so that the OH functionalities in 1,3-relationship are automatically brought into a favorable geometry for the formation of intramolecular O-H…O hydrogen bonds. Working within this paradigm, which was formulated both logically and on the basis of the observed H-bonding patterns in the crystal structures of several conformationally locked polyols, we were able to demonstrate that intramolecular H-bonding between 1,3-syndisxial OH groups can be used as a tool to preordain the position of the intermolecular O-H…O-bond donors and accepts in the specially crafted polycyclitols 1-3. this observation not only simplified a qualitative visualization of the various packing patterns in 1-3, but also allowed us to propose, based on previously reported CSD analysis, the packing motifs mostlikely to converge with the experimental results. Despite its qualitative nature, the O-H…O hydrogen bonding patters, proposed for 1-3 were found to conform well with those observed experimentally for the tetrols 1 and 3, and even for the two polymorphic modifications of the hexol 2[Figure 1] The determination role played by intramolecular O-H…O bonding in the supramolecular assembly of 2, a novel bicycle C2h symmetric hexol having an all axial disposition of the six hydroxyl functionalities, prompted us to study the crystal packing of the three diastereomeric perhydro-2,3,4q,6,6,8a-naphthalenehexols 4-6. the end-to-end co-operative intramolecular O-H…O-H hydrogen bonding chain on both faces of the molecule, as observed in case of 2, through an axial-equatorial. Figure 1. (left) one of the packing modes proposed for the hexol 2. Note that the H-bonding pattern involves all donor/acceptor oxygen and incorporates infinite chains of O-H…O bonds of O-H….O bonds; (right) Molecular packing observed experimentally in the polymorph of the hexol 2 Transposition of one or more of the peripheral yhdroyl groups. With increased freedom now allowed to the OH groups in the choice of their H-bonding partners, as a compared to 2 crystal packing in the polycyclitols 4-6 evolved from the simplistic model of hydrogen bonding proposed and observed for 2,to ivoke more complex patterns of self assembly mediated through O-H…O-bonds In the second chapter, the crystal structures of four conformationally locked esters, namely tetraaccetate 7/tetrabenzoate 8 of hexol 2 and the diacetate9/dibenzoate 10 of tetrol1,have been analyzed in order to examine the preference of their supramolecular assemblies towards competing inter and intramolecular O-H…O hydrogen bonds. To this end, all the four esters under study were specially crafted on a trans-decalin backbone with the objective of relegating the O-H…O H-bond donors( in form of the 30 OH groups) to the molecular interior and having the peripheral H-bond accepters (in form of the 20 acyl groups) in 1,3-syndiaxial relationship. It was anticipated that this common design element would allow the supramolecular assembly of the easters to evolve along two possible pathway, namely one which employs intermoleculars O-H…O H-bonds (pathway 1) and the other that sacrifises those for intramolecular O-H…O H-bonds and settles for a crystal packing dictated by weak intermolecular interactions alone (pathway 2) A pure sample of 7 crystallized along pathway 1 in two enantiotropic modifications, one obtained at room temperature (form) and the other at 20 C0 (form) [Figure 2]. Behaving much like a temperature guided molecular switch, the tetraacetate 7 could be shifted reversibly between the forms response to changes in the ambient temperature. Thus, the form converted at -4 OC to the denser form, which displayed an unusual kinetic stability till 67 OC and transformed back to the form beyond this temperature. Subsequently, the close similarity between the self-assemble of the two dimonrphs of 7 and the diastereomer 11 was exploited in order to stimulated 7 to fallow the pathway 2 through preferential inhibition of pathway 1[Figure 3]. Interstingly, the nucleation inhibition 11 was obtained serendipitously a route 7 via an apparent breakdownof furst-platter rule. Unlike the tetraceatate 7, crystal packing in the tetrabenzoate 8 preferred to fallow exclusively pathway 2. The individualistic nature of the self-assemblies of 7 and 8 found to be in contrast commonalities noted in the mode of molecular assembly in 9 and 10 both of which conformed to a combination of pathway 1 and 2. A rationale for the preferred crystallization pathway of the four estes 7-10 as well as probable mechanism for the observed reversible transformation between the forms the tetracetate 7 will be put forth in this chapter. Figure 2. (Model for pathway 1) Molecular packing in the forms of the tetraacetate 7. The non-interacting hydrogen atoms have been omitted for clarity. Figure 3. (Model for pathway 2) The nucleation inhibitor 11 and form of the tetraacetate 7. The non-interacting hydrogen atoms have been omitted in the molecular packing diagram for clarity. In light of the wide ranging application of organofluorine compounds and the ambiguity that resides over the disposition of fluorine as a H-bond accepter, the third chapter utilizes three specially designed fluorinated polycyclitols 12-14 investigate the role of covalently bonded flurine in crystal structures of lesser studied aliphatic fluorous substracts and probe its capacity to engage itself in C(sp3)-F…H-X(sp3)(X=O and/or C) H-bounding, in presence of its isostere, the hydrozyl group. Conformatonality locked with well defined spatial disposition of functional groups, all the fluorinated polycyclitols 12-14 bear a fluorohydrin moiety, embedded in a rigid trans-decalin framework. In 12 and 14, it was conceived that the presence of a hydroxyl donor in a favorable 1, 3-syndiaxial relationship to a fluoro group on one side and a hydroxyl group on the other would allow an unambiguous comparison between the two isoteric functionalities (C-OH and C-F) to serve as acceptors for intramolecular hydrogen bonds (O-H…O and purported O-H…F respectively) The difluorodiol 13 was sought to serve as a control to assess the change in the C-F…H-X interactions (if any) which might be observed upon incorporating the peripheral secondary hydroxyl groups in 14. The result presented in this chapter will revel, in particular, that C(sp3) –F…H-C(sp3) hydrogen bonds, though weak and lesser investigated, can indeed be observed and supramolecular recognition motifs, involving such interactions, can be conserved even in crystal structures laden with stronger O-H…O hydrogen bonds [Figure 4}. Figure 4. (Left) Molecular packing in the difluorodiol 13, showing how four intermolecular C-H…F hydrogen bonds forms a part of a R22 H-bonding motif (encircled). This centrosymmentic supramolecular recognition unit is observed even in the molecular packing in the difluorohexol 14 (right). Non-interacting H atoms have been omitted in both diagrams for the sake of clarity. The forth chapter details an in-depth study carried out on the self-assembly of a conformationally locked aminoalchohol 15, in which the amino protons serve as mere spectators, the molecular packing in the crystal being realized through the co-operativity between O-H…N H-bonds and weak π-π stacking interaction (Figure 5b). The crystal structure of 15 was quite intriguing on three sailent grounds (a) previous studies on the supramolecular assemblies in the aminols have shown that both amino and hydroxyl protons participate in H-bonding in the crystal structures of such compounds; (b) the fact that the hydrogen atoms of the NH2 group Figure 5. (Left) Laplacian distribution map in the planes defined by (a) the double bonds, (c) O-H…N-H-bond, and (d) π-π stacking interactions in the aminoalclhol 15. Contours havse been drawn at logarithmic intervals in ▼2 ρb, eÅ-5. Solid lines indicate positive contours and dotted lines negative contours. (b) Molecular packing in 15. Non-interacting H atoms have been omitted for the sake of clarity.remain as mere bystanders in anomalous if one were to abide by the Etter’s rule; (c) the rather well-difined π-π stacking interactions in crystal structure of the aminoalcohol occurs between isolated olefinic bonds-a rarely encountered form of non-covalent interaction. Charge destiny analysis was carried out on the aminoalcoholf 15 not only to catheterize the non-covalent interactions existing in the supramolecular assembly in terms of topological features of electrol destiny at their bond critical points, but also to confirm the non-involvement of the amino H-atoms in any form of either intra- or intermoalecular hydrogen bonds beyond the criteria of mere geometry (Figure a,c,d). The maverick nature of the self-assembly of 15 was elucidated as resulting from the preference of the molecules to assemble with O-H…N H-bonds. This automatically relegated the hydrogen atoms of the tertiary amine to the interior of the conformationally locked cabocycclic scaffold, thereby making them far less accessible than the peripheral C=C bonds.

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