Disaccharides are useful for immunological studies, the identification of isolated polymer fragments, and studies on model compounds but few have been synthesized. The syntheses of four new disaccharides of the 4-0-glycopyranosyl-L-rhamnopyranose series namely 4-0-g-D-glucopyranosyl--L-rhamnopyranose (15), 4-0-a-L-rhamnopyranosyl-L-rhamnopyranose (26), 4-0--a-D-mannopyranosyl-L-rhamnopyranose (38), and 4-0-8-D-mannopyranosyl-L--rhamnopyranose (56) are reported. The selectively substituted aglycon used for all the members of this series was methyl 2,3-0-isopropylidene-a-L-rhamnopyranoside (3) prepared by acetalation of methyl a-L-rhamnopyranoside and purified through crystalline methyl 4-0-acetyl-2,3-0-isopropylidene-a-L-rhamnopyranoside (2). Compound 2_ was deacetalated to give methyl 4-0-acetyl-a-L-rhamno--pyranoside which served as a key intermediate for the preparation of the standards 2,3-di-O-methyl-L-rhamnose and 4-deoxy-L-erythritol. Disaccharide J15_ was prepared in an overall yield of 55% based on the aglycon by first condensing 2,3,4,6 - tetra-O-acetyl-a-D-glucopyranosyl bromide with 3^ in the presence of mercuric cyanide in acetonitrile to give crystalline methyl 2,3-C-isopropylidene-4-0-(2,3,4,6-tetra-0-acetyl-g-D--glucopyranosyl)-a-L-rhamnopyranoside (10) in 80% yield based on 3_. Since the isopropylidene group of 1_0 could not be acetolyzed it was removed with trifluoroacetic acid to give methyl 4-0-(2,3,4,6-tetra-0-acetyl-B-D-gluco--pyranosyl)-a-L-rhamnopyranoside (11) . Acetolysis of n_ gave crystalline 1,2,3-tri-0-acety1-4-0- (2,3,4,6-tetra-0-acetyl-i3-D - glucopyranosyl)-a-L--rhamnopyranose (14). Deacetylation of 1_1_ gave the methyl glycoside of the disaccharide which, as for the subsequent disaccharides, was subjected to methylation and periodate oxidation studies to confirm the 1,4 linkage. An improved method for the quantitation of periodate oxidation degradation products is described. Deacetylation of 1_4_ gave L5_ which was reduced to give 4-0-B-D-glucopyranosyl-L-rhamnitol which upon acetylation gave crystalline 1,2,3,5-tetra-C-acetyl-4-0-(2,3,4,6-tetra-O-acetyl-g-D-glucopyran--osyl)-L-rhamnitol. In an analogous manner disaccharides 26_ and 38 were prepared in overall yields of 60 and 55% based on the aglycon by condensing 2,3,4-tri--O-acetyl-a-L-rhamnopyranosyl bromide and 2,3,4,6-tetra-O-benzoyl-a-D--mannopyranosyl bromide respectively with _3. The deblocking procedures paralleled those of the D-gluco analog. Disaccharide 26_ was characterized as crystalline methyl 2,3-di-0-acetyl-4-0-(2J3,4-tri-C-acetyl-a-L-rhamno--pyranosyl)-ct-L-rhamnopyranoside, 1,2,3-tri-O-acetyl-4-0-(2,3,4-tri-O-acetyl--a-L-rhamnopyranosyl)-a-L-rhamnopyranose, and 1,2,3,5-tetra-C-acetyl-4-0--(2,3,4-tri-0-acetyl-a-L-rhamnopyranosyl)-L-rhamnitol. Disaccharide 38^ was crystalline and was also characterized as crystalline 1,2,3-tri-c7-acetyl-4--0-(2,3,4,6-tetra-O-acetyl-a-D-mannopyranosyl)-a-L-rhamnopyranose and l,2,3,5-tetra-0-acetyl-4-0-(2,3,4,6-tetra-O-acetyl-a-D-mannopyranosyl)-L--rhamnitol. A combined reduction acetylation procedure for the 2,3-di-O--methyl-L-rhamnose obtained from methylated 26 produced a boron-containing derivative of 2,3-di-O-methyl-L-rhamnitol. Proton magnetic resonance spectroscopy was used to substantiate the configuration of the linkage in these disaccharides. A general method for the synthesis of 3-D-mannopyranosides was developed to synthesize disaccharide 56^. This was done by preparing 4,6- -di-0-acetyl-2,3-0-carbonyl-a-D-mannopyranosyl bromide (44) through sequential formation of the carbonate, acetolysis, and bromination of methyl 4 ,.6-0-benzylidene-a-D-mannopyranoside. Bromide 44 was condensed with methanol to give crystalline methyl 4,6-di-0-acetyl-2,3-0-carbonyl-g--D-mannopyranoside (45) in 87% yield. Deacylation of 45_ gave methyl 3-D--mannopyranoside which was characterized as its crystalline isopropylate and peracetate. Disaccharide 5_6_ was prepared in an overall yield of 50% based on the aglycon by condensing 44 with 3_ in the presence of silver oxide in chloroform. The deblocking procedures were similar to those for the previous disaccharides. Acetolysis of the disaccharide intermediates in the sequence was profoundly influenced by the presence of the cyclic carbonate group. Disaccharide 5_6_ was characterized as crystalline methyl 4-0-8-D-mannopyranosyl-a-L-rhamnopyranoside isopropylate and 1,2,3-tri-O--acety1-4-0-(2,3,4,6-tetra-0-acetyl-B-D-mannopyranosyl)-a-L-rhamnppyranose. / Science, Faculty of / Chemistry, Department of / Graduate

A multistep synthesis of a monoraethylated beta linked disaccharide of biological significance, 6-O-(4-O-methyl-0-D-glucopyranosyl)-D-galactose is described for the first time. A key intermediate in this synthesis was 4-0-methyl-D-glucose, which was obtained by a synthetic route involving open chain carbohydrate derivatives, and by isolation from mesquite gum, a polysaccharide that contains ^-O-methyl-D-glucose as the uronic acid. Condensation of the derived 2,3,6-tri-0-acetyl-4-0-methyl-CL-D-glucopyranosyl bromide with 1,2»3»^-di-O-isopropylidene-a-D-galactopyranose and subsequent removal of the blocking groups afforded 6-O-(4-O-methyl-0-D-glucopyranosyl)-D-galactose in 55% yield. The synthesis of alpha linked glucosides using 0-D-gluco-pyranosyl bromides having a non-participating benzyl group at C-2 has been investigated. Two of these bromides were used in glycoside forming reactions, 2-0-benzyl-3,4,6-tri-0-p_-nitrobenzoyl-P-D-gluco-pyranosyl bromide, and 2,3-di-0-benzyl-^,6-di-0-p_-nitrobenzoyl-p-D-glucopyranosyl bromide. The preparation of a glucosyl bromide having a non-participating 2,3-carbonate function was attempted, but was unsuccessful. Isomaltose and 6-0-a-D-glucopyranosyl-D-galactose were prepared using the 2,3-dibenzyl compound. Isomaltose, 6-0-a-D-glucopyranosyl-D-mannose and 4-0-cu D-glucopyranosyl-L-rhamnose were synthesized using the 2-benzyl compound. The latter disaccharide represents the first a-linked glucoside containing L-rhamnose to be synthesized. The synthesis of several methylated sugars useful for the analysis of polysaccharide structures is described. 73-O-Methyl-D-galactose was prepared in a multistep synthesis involving l,2i 5,6-di-O-isopropylidene-a-D-galactofuranose. Finally, a new synthesis of 3»^»6-tri-O-methyl-D-glucose, D-galactose and D-mannose is described. / Science, Faculty of / Chemistry, Department of / Graduate

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Abstract The highly radioresistant Deinococcus radiodurans is a heterotrophic Gram positive aerobic tetrad. The addition of 2.5 uM Mn(II) into the early stationary-phase culture would trigger a new round of cell division (Mn-CD effect) which is specific to this unique bacterium. In order to understand the reactions of this bacterium to different carbohydrates, we culture the bacterium by using complex media with various monosaccharides and disaccharides. No matter in the present of Mn(II) or not, the specific growth rate of fructose¡Vgrown cells was always higher than those of glucose-grown cells. Cell growth would be inhabited by excess Mn(II). Along with the increasing of Mn(II), the culture showed a prolonged lag phase. In chemically defined media, this bacterium grew well by using glucose, fructose, mannose, maltose or sucrose as it¡¦s sole carbon source and performed the Mn-CD growth by adding Mn(II). II

Thesis (Ph.D.)--Tufts University, 2001. / Adviser: Marc d'Alarcao. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 210-218). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

by Stanton Hon-Lung Kok. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 142-147). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.