C-H bonds are easily the most common type of ordinary chemical bond and studying carbon acidity will help us understand and predict the reactivity of organic compounds. Carbon acidities are ranked using acidity scales. One of the most prominent is the Streitwieser Lithium Indicator (SLI) scale. The term "indicator scale" implies that acids have been measured against one another in sequential fashion. The SLI scale uses lithium ion as the conjugate-base counterion and THF as the solvent. Historically, the SLI scale has emphasized the characterization of weakly-acidic hydrocarbons. Prior to the work of our group, the strongest acid on the SLI scale has a pK value of about 10. Deck and Thornberry extended the scale to ca. pK = 0 by evaluating 23 perfluoroaryl-substituted cyclopentadiene and indene derivatives, using 19F NMR spectroscopy to determine the equilibrium constants of sequential acid-base reactions. This thesis describes the further extension of the SLI scale to ca. pK = −6. To achieve this result, a set of 11 tetrasubstituted cyclopentadienes were synthesized and their acidities evaluated sequentially with the goal of reaching a low pK value while minimizing the acidity ratio at each incremental step. The four ring substituents were combinations of pentafluorophenyl, perfluoro-4-tolyl, and perfluoro-4-pyridyl, electronegative groups listed in order of increasing electron-withdrawing power. The most acidic compound in the set was 1-pentafluorophenyl-2,3,4-tetrakis(tetrafluoro-4-pyridyl)cyclopentadiene, having pK = −5.99. Trends in the acidities of tetraarylcyclopentadienes are discussed including relative electron-withdrawing power of the three selected substituents, and conformational effects among pairs of regioisomeric cyclopentadiene derivatives. / Master of Science / Carbon acidity refers to the willingness of a carbon-hydrogen bond to release a hydrogen ion. C-H bonds are easily the most common type of ordinary chemical bond, so it makes sense that studying carbon acidity will help us understand and predict the reactivity of organic compounds. For the past several decades, emphasis in this area of research has focused on weak carbon acids, especially the simplest hydrocarbons like benzene and methane. This thesis aims in the opposite direction of synthesizing and measuring stronger and stronger carbon acids until we reach the theoretical limit for a given solvent. Because our research strategy is inherently incremental, compounds were synthesized and their acidities were measured, drawing close to the theoretical limit using tetrahydrofuran as the solvent.

<p>Glycoconjugates are biologically important molecules with diverse functions. They consist of carbohydrates of varying size and complexity, attached to a non-sugar moiety as a lipid or a protein. Glycoconjugate structures are often very complex and their intricate biosynthetic pathways makes overexpression difficult. This renders the isolation of pure, structurally defined compounds from natural sources cumbersome. Therefore, to better address questions in glycobiology, synthetic glycoconjugates are an appealing alternative. In addition, synthetic methods allow for the preparation of non-natural glycoconjugates that can enhance the understanding of the influence of structural features on the biological responses.</p><p>In this thesis, synthetic methods for the preparation of glycoconjugates, especially glycolipid analogues, have been developed. These methods make use of solid-phase chemistry and are amenable to library synthesis of series of similar compounds. Solid-phase synthesis is a technique where the starting material of the reaction is attached to small plastic beads through a linker. This allows large excess of reagents to speed up the reactions and the sometimes difficult purifications of intermediate products are reduced to simple washings of the beads.</p><p>One problem with solid-phase synthesis is the difficulties to monitor the reactions and characterize the intermediate products. Gel-phase 19 F-NMR spectroscopy, using fluorinated linkers and protecting groups, is an excellent tool to overcome this problem and to monitor solid-phase synthesis of e.g. glycoconjugates. Two novel fluorinated linkers for the attachment of carboxylic acids have been developed and are presented in the thesis. These linkers can be cleaved with both acids of varying strengths and nucleophiles like hydroxide ions, and they are stable to glycosylation conditions. In addition, a novel filter reactor for solid-phase synthesis was designed. The reactor fits into an ordinary NMR spectrometer to facilitate the reaction monitoring with gel-phase 19 F-NMR spectroscopy.</p><p>The biological applications of the synthesized glycolipids were demonstrated in two different settings. The CD1d restricted binding of glycolipids carrying the monosaccharide α-GalNAc as carbohydrate could be detected on viable cells of mouse origin. CD1d is one of several antigen presenting molecules (the CD1 proteins) that presents lipids and glycolipids to circulating T-cells that in turn can initiate an immune response. The CD1 molecules are relatively sparsely investigated, and the method to measure glycolipid binding on viable cells, as described in the thesis, has the possibility to greatly enhance the knowledge of the structural requirements for CD1-binding.</p><p>Serine-based neoglycolipids with terminal carboxylic acids were used to prepare glycoconjugate arrays with covalent bonds to secondary amines on microtiter plates. Carbohydrate arrays have great possibilities to simplify the study of interactions between carbohydrates and e.g. proteins and microbes. The usefulness of the glycolipid arrays constructed in the thesis was illustrated with two lectins, RCA120 from Ricinus communis and BS-1 from Bandeiraea simplicifolia. Both lectins bound to the array of neoglycolipids in agreement with their respective specificity for galactosides.</p><p>Glycobiology is a large area of great interest and the methods described in this thesis can be used to answer a variety of glycoconjugaterelated biological questions.</p>

Glycoconjugates are biologically important molecules with diverse functions. They consist of carbohydrates of varying size and complexity, attached to a non-sugar moiety as a lipid or a protein. Glycoconjugate structures are often very complex and their intricate biosynthetic pathways makes overexpression difficult. This renders the isolation of pure, structurally defined compounds from natural sources cumbersome. Therefore, to better address questions in glycobiology, synthetic glycoconjugates are an appealing alternative. In addition, synthetic methods allow for the preparation of non-natural glycoconjugates that can enhance the understanding of the influence of structural features on the biological responses. In this thesis, synthetic methods for the preparation of glycoconjugates, especially glycolipid analogues, have been developed. These methods make use of solid-phase chemistry and are amenable to library synthesis of series of similar compounds. Solid-phase synthesis is a technique where the starting material of the reaction is attached to small plastic beads through a linker. This allows large excess of reagents to speed up the reactions and the sometimes difficult purifications of intermediate products are reduced to simple washings of the beads. One problem with solid-phase synthesis is the difficulties to monitor the reactions and characterize the intermediate products. Gel-phase 19 F-NMR spectroscopy, using fluorinated linkers and protecting groups, is an excellent tool to overcome this problem and to monitor solid-phase synthesis of e.g. glycoconjugates. Two novel fluorinated linkers for the attachment of carboxylic acids have been developed and are presented in the thesis. These linkers can be cleaved with both acids of varying strengths and nucleophiles like hydroxide ions, and they are stable to glycosylation conditions. In addition, a novel filter reactor for solid-phase synthesis was designed. The reactor fits into an ordinary NMR spectrometer to facilitate the reaction monitoring with gel-phase 19 F-NMR spectroscopy. The biological applications of the synthesized glycolipids were demonstrated in two different settings. The CD1d restricted binding of glycolipids carrying the monosaccharide α-GalNAc as carbohydrate could be detected on viable cells of mouse origin. CD1d is one of several antigen presenting molecules (the CD1 proteins) that presents lipids and glycolipids to circulating T-cells that in turn can initiate an immune response. The CD1 molecules are relatively sparsely investigated, and the method to measure glycolipid binding on viable cells, as described in the thesis, has the possibility to greatly enhance the knowledge of the structural requirements for CD1-binding. Serine-based neoglycolipids with terminal carboxylic acids were used to prepare glycoconjugate arrays with covalent bonds to secondary amines on microtiter plates. Carbohydrate arrays have great possibilities to simplify the study of interactions between carbohydrates and e.g. proteins and microbes. The usefulness of the glycolipid arrays constructed in the thesis was illustrated with two lectins, RCA120 from Ricinus communis and BS-1 from Bandeiraea simplicifolia. Both lectins bound to the array of neoglycolipids in agreement with their respective specificity for galactosides. Glycobiology is a large area of great interest and the methods described in this thesis can be used to answer a variety of glycoconjugaterelated biological questions.

<p>An efficient and versatile non-destructive method to analyze the progress of solid-phase glycoconjugate synthesis with gel-phase ¹⁹F NMR spectroscopy is described. The method relies on use of fluorinated linkers and building blocks carrying fluorinated protective groups. Commercially available fluorinated reagents have been utilized to attach the protective groups. </p><p>The influence of resin structures for seven commercial resins upon resolution of gel-phase ¹⁹F NMR spectra was investigated. Two different linkers for oligosaccharide synthesis were also developed and successfully employed in preparation of α-Gal trisaccharides and a n-pentenyl glycoside. Finally, reaction conditions for solid-phase peptide glycosylations were established.</p>

An efficient and versatile non-destructive method to analyze the progress of solid-phase glycoconjugate synthesis with gel-phase 19F NMR spectroscopy is described. The method relies on use of fluorinated linkers and building blocks carrying fluorinated protective groups. Commercially available fluorinated reagents have been utilized to attach the protective groups. The influence of resin structures for seven commercial resins upon resolution of gel-phase 19F NMR spectra was investigated. Two different linkers for oligosaccharide synthesis were also developed and successfully employed in preparation of α-Gal trisaccharides and a n-pentenyl glycoside. Finally, reaction conditions for solid-phase peptide glycosylations were established.

Mucin is a term used to describe a large family of heavily glycosylated proteins which are present on the surfaces of secretory epithelial cells and are overexpressed by many carcinomas. Membrane-bound mucin MUC1 is of special interest. Its backbone consists of repeating units of twenty amino acids with five potential glycosylation sites. These sites are expanded to structures like the T (Galβ(1-&gt;3)GalNAcα-Ser/Thr) and Tn (GalNAcα-Ser/Thr) antigens by the action of various glycosyltransferases. In different types of carcinomas these epitopes are being terminated by sialic acid residues to form among others: 2,3-sialyl-T and sialyl-Tn structures due to the elevated levels of different sialyltransferases. Solid-phase synthesis of the selected antigens derived from the mucin MUC1 has been developed and optimized. A chemoenzymatic approach has been used to effectively prepare 2,3-sialyl-T and 2,6-sialyl-Tn glycopeptides. The formation of intramolecular sialic acid lactones in presence of acetic acid was investigated. The stability of lactones formed from 2,3-sialyl-T towards water was studied using NMR spectroscopy and it appeared that 1''-&gt;2' lactone displayed remarkable strength to hydrolysis and it was suggested as a candidate for cancer vaccine. Gel-phase 19F NMR spectroscopy is known to be a very good tool to characterize resin-bound products using fluorinated protecting groups and linker molecules. The hydrophobic peptide LLLLTVLTV, which is a fragment from the MUC1 signal sequence, was prepared using solid-phase synthesis according to a modified Fmoc protocol with more active coupling reagent, stronger base, and the isopropylidene dipeptide Fmoc-Leu-Thr-(ΨMe,Mepro)-OH. Gel-phase 19F NMR spectroscopy was used to evaluate peptide chain aggregation and coupling and deprotection efficiency. A carbamate linker strategy proved to be effective in solid-phase synthesis of serine-based neoglycolipids with terminal amino functionality. Neoglycolipids were covalently bound to secondary amines in microtiter plates using squaric acid ester methodology. These arrays have potential to study the interactions between carbohydrates and e.g. proteins and microbes. The new fluorinated α-amino protective group [1-(4-(4-fluorophenyl)-2,6-dioxocyclohexylidene)ethyl] Fde was developed. This group is cleaved with hydrazine in DMF solution. By using amino acids protected with this group, it was possible to quantify the efficiency of peptide coupling using gel-phase 19F NMR spectroscopy.

Die vorliegende Arbeit befasst sich mit mechanistischen Untersuchungen der fluorolytischen Sol-Gel-Synthese von nano-Magnesiumfluorid, sowie verschiedenen Abwandlungen der bekannten Synthese zur gezielten Veränderung der Eigenschaften der erhaltenen Materialien. Es werden die drei im folgenden beschriebenen Themenbereiche behandelt: Der Verlauf der Fluorolyse von Magnesiummethoxid mit methanolischer HFLösung wird mit der 19F-NMR-Spektroskopie über sechs Monate untersucht. Es wird gezeigt, dass MgF2-Nanopartikel, Agglomerate von gestörten MgF2-Partikeln und nicht umgesetzte, adsorbierte HF-Spezies in den Solen nachweisbar sind. Erstmalig werden MAS-NMR-Experimente an Solen beschrieben. Zusätzlich wird die schrittweise Fluorolyse von MgCl2 mittels NMR-Spektroskopie und XRD untersucht. Es werden drei verschiedene Synthesewege vorgestellt, mit denen eine Veränderung von Partikel- oder Kristallitgrößen erreicht wird. Eine sequentielle Synthese ermöglicht die Vergrößerung der Agglomerate im Sol. Das Erhitzen eines Sols zum Sieden unter Rückflusskühlung führt zu einem geringfügigen Anwachsen der Kristallitgröße. Durch Solvothermal-Synthesen wird eine signifikante Vergrößerung der Kristallite erzielt. Der Einfluss verschiedener Reaktionsparameter wird untersucht. Der Einfluss von MgF2 auf die Kristallisation von amorphem TiO2 wird untersucht. Es wird gezeigt, dass die Sol-Gel-Synthese von TiO2 in Gegenwart eines MgF2-Sols (min. 5 mol%) zur Kristallisation von Rutil-TiO2 bei vergleichsweise niedrigen Temperaturen führt. Verschiedene alternative Synthesen werden vorgestellt, durch die bei vergleichbaren Bedingungen nur Anatas-TiO2 erhalten werden kann. Ein möglicher Mechanismus der Strukturinduktion wird vorgeschlagen. / The present Ph.D. thesis deals with mechanistic investigations of the fluorolytic sol-gel synthesis of nano magnesium fluoride. Furthermore, variations of the well known synthesis are introduced. The aim of these variations is to tailor the properties of the synthesized materials. The thesis covers three main chapters briefly introduced below: The course of the fluorolysis of magnesium methoxide with methanolic HF-solution will be monitored for six months using 19F NMR spectroscopy. The existence of MgF2 nanoparticles and agglomerates of disturbed MgF2 particles will be proven. It is demonstrated that hydrogen fluoride does not react immediately after the addition of HF-solution. For the first time MAS-NMR experiments of sols will be conducted. Furthermore, stepwise fluorolysis of magnesium chloride will be followed by NMR spectroscopy and X-ray diffraction. In this case no intermediates will be detected. Three different synthetic approaches capable of tailoring the crystallite and particle sizes will be presented. Using a sequential synthesis leads to increased size of the agglomerates in the sols. It will be demonstrated that heating and refluxing of a sol increases the crystallite size slightly. Solvothermal synthesis will be the last method leading to significant increase in crystallite sizes. Several synthetic parameters will be varied to identify their influence on the received crystallites. The influence of nano MgF2 on the crystallisation of amorphous TiO2 is investigated. It will be shown, that the sol-gel synthesis of TiO2 in the presence of a MgF2 sol leads to the crystallisation of the rutile polymorph of TiO2. The temperature treatment for that is comparatively low and just 5 mol% MgF2 are necessary. Furthermore, a different alternative synthesis will be introduced, that gives the anatase polymorph at the same conditions. Eventually a possible mechanism for the structural induction is proposed.

To study the functions of glycoconjugates in biological systems reliable and efficient protocols for glycoconjugate synthesis are needed. To reach this goal we have developed methods for solid-phase synthesis of glycoconjugates that can be monitored with gel-phase 19F spectroscopy using fluorinated linkers, building blocks, and protecting groups. We have developed a new fluorine containing linker suitable for solid-phase synthesis of glycoconjugates. The linker was more acid-labile than similar linkers in order to enable cleavage under mild conditions of the target compound from the linker resin.  A carbamate-based strategy has been applied to attach a spacer carrying an amino group to a fluorinated Wang linker for synthesis of amino-functionalized glycoconjugates using thioglycoside donors with fluorinated protective groups. Cleavage from the solid support was performed with trifluoroacetic acid and subsequent protecting group removal gave the target compound. The terminal amine was conjugated with didecyl squarate and this derivative can be attached to various proteins and solid surfaces carrying primary or secondary amines. To evaluate this methodology we have immobilized glycoconjugates in amino-functionalized microtiter plates and successfully probed them with lectin. In addition, a novel fluorine containing protecting group has been designed, synthesized and evaluated. The protecting group was used for protection of the unreactive 4-OH in a galactose building block that was applied in the synthesis of 6-aminohexyl galabioside and was removed with TBAF in THF. Adenovirus serotype 8 (Ad8), Ad19, and Ad37 cause the severe ocular infection, epidemic keratoconjunctivities (EKC). During infection, the adenoviruses interact with sialic acid containing glycoconjugates on the epithelial cells via fiber structures extending from the viral particles. The virus particle most likely binds to the host cell in a multivalent way by simultaneously using multiple fiber proteins and binding sites. Multivalent sialic acid containing conjugates could efficiently inhibit Ad37 cell attachment and subsequent infection of human corneal epithelial (HCE) cells. Three compact tri- and tetravalent sialic acid conjugates were prepared and evaluated as inhibitors of adenoviral host cell attachment and subsequent infection and all conjugates were potent as anti-adenoviral agents. The conjugates can readily be synthesized from accessible starting materials. A crystal structure of the Ad37 fiber knob protein and the trivalent sialic acid conjugate showed that the three binding sites were all occupied by one sialic acid residue each.