Thesis (Ph. D.)--University OF MICHIGAN.

Thesis (Ph. D.)--University OF MICHIGAN.

Thesis (Ph. D.)--University OF MICHIGAN.

N-Acetylneuraminic acid (NeuAc) is a sialic acid which constitutes terminal positions in glycoproteins and glycolipids. It is part of the antigenic determinant of many forms of cancer (S. Hakomori, Chem. Phys. Lipids. 42, 209 (1986)) and hence a cancer "vaccine" could be made from an appropriate multivalent macromolecular form of NeuAc. To explore the possibility of inducing anti-NeuAc antibodies, we have synthesized polyvalent conjugates of $\alpha$NeuAc or NeuAc$\alpha$2-3Gal$\beta$1-4Glc (sialyl2-3lactose) on protein carriers. This was accomplished by reductive amination with 2-oxoethyl $\alpha$-NeuAc or with the concealed aldehyde of the reducing sugar (glucose) onto the lysine residues of the proteins Bovine Serum Albumin (BSA) and Tetanus Toxoid (TT). A new procedure involving a Michael-type addition employed the $\epsilon$-amino groups of the lysine residues in a 1,4 nucleophilic addition to the acrylamide functional group in two derivatives of NeuAc; the N-acryloylaminoethylthiopropyl glycoside, and the N-acryloylsialyl2-3lactosylamine. This technique does not require the use of reagents and was performed under mild basic conditions. Polyacrylamide copolymers were also synthesized by radical co-polymerization of acrylamide with NeuAc monomers, providing a polymer (Mw $\approx$ 100 kDa) with pendant NeuAc. Reactive monomers giving different spacer arms between the sugar and the polymer backbone were developed, including the allyl glycoside, a more reactive N-acryloylaminoethylthiopropyl glycoside and several lactose derivatives. The polymers were found to have a better shelf life than the proteins, and had the advantage of sharing only the NeuAc moiety. Some of the NeuAc/protein conjugates were used to immunize rabbits, and the antibodies formed were screened with polyacrylamide copolymers with pendant NeuAc. The polymer with spacer was found to react better with the antibodies in immunoprecipitation and enzyme-linked immunosorbent assay (ELISA). Inhibition of ELISA experiments were done using synthesized derivatives of NeuAc to determine the binding specificity of the antibodies. It was found that the antibodies recognized the glycerol side chain, acid function, spacer, and to a lesser extent, the acetamido function of NeuAc. The same methodology was used to map the binding site of the lectin from Triticum vulgaris (called Wheat germ agglutinin, WGA) which binds NeuAc. Nuclear magnetic resonance (nmr) studies were undertaken to determine the acidity constants (pK$\sb{\rm a}$) and conformation of several NeuAc derivatives. Also studied was the lactone of NeuAc$\alpha$2-3Gal$\beta$1-4Glc which is believed to be responsible for the immunogenicity of certain cancer cells (T. Dohi, G. Nores and S. Hakomori, Cancer Res. 48, 5680 (1988)). This work was complemented by molecular modelling using MM2. A model was proposed for the conformation of the lactone which is consistent with the n.m.r. evidence.

The tetrasaccharide sialyl Lewisx (SLex) is the smallest recognizable ligand for selectins. The binding of SLe x to the selectins triggers the inflammatory cascade and recruits leukocytes to the injured cells. Chronic and acute inflammatory diseases result from the over-recruitment of leukocytes leading to damage of normal cells. Carbohydrate-based mimetics, maintaining functionality while improving stability, binding affinity and structural simplicity, are ideal candidates for anti-inflammatory drugs. Sialyl Lewisx glycomimetics were synthesized using two different convergent approaches. Each synthesis used an enzyme-resistant alpha-carbon-linked fucosyl moiety (C-glycoside) to replace the unstable anomeric oxygen linkage of the natural ligand. One synthetic route coupled a rigid proline ring to the fucosyl carboxylic acid derivative made from L-fucose to form one branch of the mimetic. The second branch was synthesized by coupling modified amines to form functionalized peptide chains of various lengths. The second convergent approach used novel olefin metathesis chemistry in the preparation to orchestrate a stereoselective cis-alkene bond formation extending from the fucosyl branch of the synthetic pathway. (Abstract shortened by UMI.)

A novel synthetic strategy for the potential analogue 17 of the immunosuppressive agents subglutinols A (3) and B ( 4) was investigated. Neither of these molecules, nor any analogues, have been synthesized previously. The route selected employed a cis -isopropylidene control group in the tether to facilitate the key synthetic step, an intramolecular Diels-Alder reaction. This approach afforded the tricyclic core of 18 in an efficient and direct manner. The Diels-Alder precursor 20 was constructed from D-isoascorbic acid (24), vinylmagnesium chloride (22), and 4-iodo-3-methoxymethoxymethyl-penta-1,3-diene (21). The synthesis of the lactone 19 and the attempts to remove the MOM group from 18 were also investigated. Unfortunately, however, the final target analogue 17 was not realized due to unsuccessful attempts at removing the MOM group from 18. Thus, an efficient route to the decalin core was established, though the coupling of the lactone 19 awaits further study.

No description available.

The syntheses of 8-amino-16-azadispiro[6.1.6.2]heptadecan-16-one and its 8-chloroacetyl derivative are reported. The compounds were characterized by their infrared spectra and by elemental analysis of the latter compound. Data is presented for the attempted reaction of dimethylaminoacetic acid with 7-amino-14-azadispiro[5.1.5.2]pentadecan-15-one and 8-amino-16-azadispiro-[6.1.6.2]heptadecan-17-one using dicyclohexylcarbodiimide as the condensing reagent. The reduction of the product obtained from the latter reaction is described. The addition of the ß-dimethylaminoethyl group to the 8-amino dispiro compound named above, in the presence of sodamide was also tried. A ß-dimethylaminoethyl derivative of 7,14-diazadispiro[5.1.5.2]penta-decane was synthesized by the lithium aluminum hydride reduction of the pentadecan-15-one analog. A correct elemental analysis was obtained for the unsaturated compound but the reduced derivative was identified only by its infrared spectrum. It was not determined whether substitution had occurred at the secondary or the lactam nitrogen. The reaction of chloroacetyl chloride with 7,14-diazadispiro[5.1.5.2]pentadecan-15-one using a variety of reaction conditions is described. Data is also presented for the attempted purification of the product obtained from the latter reaction; both thin layer and column chromatography were employed. The condensation reaction of 1-amino-cycloheptanecarbonitrile in the presence of sodium ethoxide and a trace of moisture does not yield the expected 8,16-diazadispiro[6.1.6.2]heptadecan-17-one. / Pharmaceutical Sciences, Faculty of / Graduate

No description available.

No description available.