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Synthesis of sugar conjugates: metal complexes and other derivatives

University of British Columbia

A number of conjugates of carbohydrates were prepared. Metal conjugates were synthesized in two different ways. Firstly, chelate coordination complexes were synthesized by forming salicylaldimine ligands derived from combinations of amino sugars [methyl-3,4,6-tri-0-acetyl-2-amino-2-deoxy-β-D-glucopyranoside, 1,3,4,6-tetra-0-acetyl-2-amino-2-deoxy-β-D-glucopyranose or 2-amino-2-deoxy-a,β-D-glucopyranose (glucosamine)] and either salicylaldehyde or 3-formyl-2-hydroxy-benzoic acid with subsequent complexation of these to copper (II) , cobalt (II), and zinc (II). A number of physical techniques were used to characterize these complexes including esr spectroscopy, visible absorption spectroscopy, mass spectrometry, nmr spectroscopy and magnetic susceptibility measurements. From the data provided by these techniques the copper-sugar complexes derived from salicylaldehyde were found in general to have the usual bis-bidentate structure. The copper complex derived from the amino-glycoside and 3-formyl-2-hydroxy-benzoic acid was found to be binuclear in structure containing two sugar moieties and two copper atoms. The second approach to forming metal sugar conjugates consisted of synthesizing organometallic π-complexes: ferrocenyl-sugar conjugates. A variety of organic- and water-soluble compounds were formed by reaction of amino, hydroxyl, or thio sugar groups with suitably substituted ferrocene derivatives. Thus organic soluble products were obtained from combinations of the sugars [l,3,4,6-tetra-0-acetyl-2-amino-2-deoxy- β-D-glucopyranose, l-thio-2,3,4,6-tetra-0-acetyl-β-D-glucopyranose, 1,2,5,6-di-0_-isopropylidene-α-D-glucofuranose and 1,2,3,4-di-o-isopropylidene-α-D-galactopyranose] with 1 - and 1,1'-ferrocenecarbonyl chlorides, N,N-dimethylaminomethylferrocene methiodide, (1-hydroxymethylferrocene)-p-toluenesulphonate and 2,4-dichloro-6-(1-hydroxymethylferrocene)-s-triazine. Water soluble products were prepared by deacetylation of some of the above compounds and by condensation of ferrocene carboxaldehyde with glucosamine to form the corresponding Schiff's base. Proton spin-lattice relaxation rates were used to assign the substituted cyclopentadienyl rings and to determine the relative spinning rates of the substituted and unsubstituted cyclopentadienyl rings. The chemistry of cyanuric chloride (2,4,6-trichloro-s-triazine), as a general means of derivatizing carbohydrates was also investigated. Thus, metals, hydrophobic alkyl groups and nitroxide spin labels were attached in various combinations to carbohydrates. A number of monosaccharide derivatives were formed including model glycolipids and a number of polysaccharides, cellulose, agarose, Sephadex, guar gum, xanthan gum and starch were spin labelled using this chemistry. For polysaccharides, information such as extent of derivatization, evidence for a covalent bond, environment of the triazine unit and the distance between triazine units was obtained. This chemistry was also extended to derivatize Bovine Serum Albumin, microporous glass beads and aluminum oxide.

Text

2010-03-22

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http://hdl.handle.net/2429/22279

Chemistry

University of British Columbia

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