Physical Sciences and Mathematics Commons^™

Ferrocenium Salt Aided Substitution Reactions And Synthesis Of Glycosylated Curcumin Derivatives, Deva Saroja Talasila

Dissertations

Organic synthesis has been significantly advanced with the employment of transition metal complexes. The discovery of transition metal catalysts provided the synthetic community with powerful tools for accelerating reactions and making them more selective and efficient. Many chemical reactions do not happen without a catalyst.

Iron-based catalysts have several advantages for the chemical industry because it is a non-toxic and ecologically friendly metal. Our group previously found that ferrocenium cations with a 3+ oxidation state of iron-catalyzed propargylic substitution reactions at low temperatures. The sandwich structure of ferrocenes allows substituents to be introduced on the cyclopentadienyl rings, which allows for …

Stereocontrolled Mannosylation By Hydrogen-Bond-Mediated Aglycone Delivery, Catherine Alex

Dissertations

Stereocontrolled Mannosylation by Hydrogen-Bond-Mediated Aglycone Delivery

Carbohydrates are the essential bio-molecules of life as they form the forefront of interactions with receptors, proteins, pathogens, or neighboring cells. On cell-surfaces, carbohydrates are mostly found as linear or branched glycoconjugates, and a majority of them are linked via either 1,2-cis or 1,2-trans O-glycosidic linkages. There is no template-driven pathway for achieving the synthesis of glycans unlike other biomolecules like proteins and nucleic acids. The synthesis of 1,2-trans glycosides can be reliably achieved via the neighboring group assistance. The synthesis of 1,2-cis glycosides is difficult because, beyond weak anomeric effects, there are …

Towards Completely Automated Glycan Synthesis, Matteo Panza

Dissertations

Carbohydrates are ubiquitous both in nature as biologically active compounds and in medicine as pharmaceuticals. Although there has been continued interest in the synthesis of carbohydrates, chemical methods require specialized knowledge and hence remain cumbersome. The need for development of rapid, efficient and operationally simple procedures has come to the fore. This dissertation focuses on the development of a fully automated platform that will enable both experts and non-specialists to perform the synthesis of glycans. Existing automated methods for the synthesis of oligosaccharides are highly sophisticated, operationally complex, and require significant user know-how. By contrast, high performance liquid chromatography (HPLC) …

Development Of An Hplc-Based Oligosaccharide Synthesizer, Salvatore Pistorio

Dissertations

Carbohydrates are the most abundant molecules on Earth. They are involved in a wide range of fundamental biological processes: anti-inflammation, immune response, joint lubrication, cell growth, antigenic determination. Carbohydrates are also held responsible for many damaging cellular processes, such as bacterial and viral infections, development of tumors, etc.. Therefore, the development of effective methods for the synthesis of complex carbohydrates has become a critical area of glycosciences. One challenge that stands out is the stereocontrol in the synthesis of glycosidic bonds, the linkage that serves as the only means to connect simple monosaccharides into complex oligomeric networks. Beyond this, the …

Templated Oligosaccharide Synthesis, Jia Guang Xiao

Dissertations

Glycosyl transfer within the active site of an enzyme involves the arrangement of the gly-cosyl donor and glycosyl acceptor in close proximity to each other. To mimic this pro-cess, intramolecular glycosylations are carried out where the donor and acceptor are linked together via a spacer. Correct orientation, rigidity and position of the spacer play a vital role in the selectivity and yield of reactions in this “molecular clamp method”. Though current methodologies show promising results in terms of yield and selectivity, the need to synthesize different complexes to ensure selectivities in all types of glycosidic linkages is a large deterrent …

Picolinyl-Assisted Approaches To Stereocontrolled Glycosylation, Jagodige Prithika Yasomanee

Dissertations

Although carbohydrates are the most abundant molecules on Earth, our current knowledge of these fascinating natural compounds is still limited. Some aspects that are already known include the carbohydrate involvement in damaging cellular processes such as bacterial and viral infections, development of tumors, metastasis, septic shock, etc. Consequently the development of effective methods for the synthesis, isolation, analysis, and investigation of complex carbohydrates has become critical in all areas of glycoscience. Among various focus areas, stereocontrolled glycosylation has emerged as a topic of particular importance. Yet, it remains a remarkable challenge to chemists because a new chirality center is formed …

Glycosyl Thiocarbamates As New Building Blocks For Chemical Glycosylation, Sneha Chandrashekhar Ranade

Dissertations

Having multiple functions in biological systems e.g. fertilization, blood group determination, cell growth; carbohydrates have remained attractive subjects for the study. They are also involved in various life threatening biological processes, such as viral and bacterial infections, tumor development, etc. Understanding of these involvements/interactions of carbohydrates in such critical processes is essential for the development of carbohydrate based vaccines and therapeutics. Although carbohydrates are present abundantly in nature, their isolation is cumbersome and low yielding, which is why, the synthesis of carbohydrate units has been of interest to many scientists. Efforts have been made to make these synthetic methods more …