2-Bromoethyl glycosides: synthesis and characterisation (original) (raw)
Related papers
A new approach to the synthesis of glycosides
Pure and Applied Chemistry, 1993
An new approach towards glycosides, which obviates the use of promoters and depends upon the acihty of the glycosyl acceptor is proposed to achieve regioselective glycosidation. Glycosylidene mbenes, generated under thermal or photolytic conditions from 0benzylated or 0-acylated 1-azi-glycoses, or from glycono-l,5-(or 1,4)-lactone tosylhydrazones react with hydroxy compounds to yield glycosides. The preparation of these precursors, their structure, their thermal stability, and their products of thermolysis are discussed. A mechanism is proposed to explain and predict the reaction of 1-azi-glycoses with mono-, di-, and triols. Protonation of the carbene in the o-plane leads to an ion-pair, which cannot immediately form glycosides. The fate of this ion pair depends upon the pK of the glycosyl acceptor, inter-and intramolecular hydrogen bonds, the direction of H-bonds, the presence of a neighbouring group at C(2), the configuration of the glycosyl acceptor, the solvent, and the temperature. Strongly acidic hydroxy compounds give glycosides in high yields and stereoselectively. Successful regio-and stereoselective glycosidation of diols and triols depends strongly upon intra-(and inter)molecular hydrogen bonds, both between the hydroxy goups of the acceptor and between functional groups of the donor and hydroxy groups of the acceptor. This is illustrated by a number of significant cases. For some of them, regioselectivity is complementary to the one observed in glycosidations of the Koenigs-Knorr-type, for others it is not. Reasons for this are discussed. Other cases present the preferential glycosylation of secondary hydroxy groups in the presence of a primary one, and the selective formation of aD -glycosides of M A C and GlcNAc. Intramolecular reactions of alkoxyalkyl carbenes are illustrated by a new method for the formation of benzylidene acetals under basic conditions, and by a new synthesis of homobenzofurans. New reactions, leading to the formation of C,C bonds at the anomeric centre are presented: the synthesis of spiro-oxiranes, of dialkoxy-spiro-cyclo opanes, and of the first glycosylated, enantiomdcally pure derivatives of Cmbuckminst&erene.
]A potentially versatile synthesis of glycosides
Carbohydrate Research, 1973
Phenyl I-thio-D-glucopyranosides in the presence of mercury(H) salts are readily solvolysed to give all@ D-glucopyranosides with inverted anomeric configuration. Methanolyses of the #? and CI anomers afford the methyl tl-and p-glycosides which were isolated in yields of 74 and 87%, respectively; n.m.r. examinations indicated that, whereas the /?-glycoside was produced stereospecifically, the a-glycoside was formed together with-6% of its /I isomer. The approach can be extended to the synthesis of complex glycosides (the a anomers of which are of special interest) as was illustrated by the preparation of cholestanyl and 1-naphthyl a-o-glucopyranoside and a disaccharide derivative.
Carbohydrate Research, 1988
In a previous paper in this series2, we outlined our interest in the synthesis of some oligosaccharides containing ~-fume a-(1+3)-link4 to 2-acetamido&deoxy-~glucose. Our interest in this class of compounds was, to a large extent, motivated by a desire to obtain reference compounds in studies related to (1+3)-CAL-fucosyltransferase. This interest was, however, enhanced by recent reports associating a variety of such oligosaccharide suuctures with certain types of human ca11cers3-~.
[Synthesis of aminoethyl glycosides of the carbohydrate chains of glycolipids Gb3, Gb4 i Gb5]
Bioorganicheskaia khimiia
4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-beta- D-glucopyranoside with ethyl 2,3,4,6-tetra-O-benzyl- and ethyl 3-O-acetyl-2,4,6-tri-O-benzyl-1-thio-alpha-D-galactopyranoside in the presence of methyl trifluoromethanesulfonate led to trisaccharide 2-azidoethyl (2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl)-(1-->4)- (2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-(1-->4)2,3,6-tri-O- benzoyl-beta-D-glucopyranoside and its 3"-O-acetylated analogue, 2-azidoethyl (3-O-acetyl-2,4,6-tri-O-benzyl- alpha-D-galactopyranosyl)-(1-->4)-(2,3,6-tri-O-benzoyl-beta-D- galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside, in yields of 85 and 83%, respectively. Deacetylation of the latter compound and subsequent glycosylation with 4-trichloroacetamidophenyl 3,4,6-tri-O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-beta-D- galactopyranoside and 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetr...
Carbohydrate research, 1987
Boron trifluoride etherate-induced glycosidation of 3-bromo-2-bromomethylpropan-l-01 with sugar acetates gave the title glycosides of the following sugars of the D series: Glcp, Galp, GlcpA, GlcNPhthp, Xylp, /3-Galp-(l-+4)-Glcp, and (Y-Galp-(l-+4)-Galp. Treatment of the fully acetylated glycosides with alkanethiols and cesium carbonate in NJ-dimethylformamide followed by deacetylation gave the corresponding bis-sulfide glycolipids. Glycolipids are localised in the outer half of cell-surface membrane bilayers where, inter a&a, they exert different biological receptor functions1-3. Although unnatural synthetic glycolipids (neo-glycolipids) have been prepared4, apparently there has been no report on the synthesis of neo-glycolipids that mimic the structure and amphiphilic properties of the naturally occurring compounds. We now describe the synthesis of some such neo-glycolipids related to 1-3. Neo-glycolipids are useful in biological receptor studies for coating of thinlayer plates, microtiter wells and cells, and for forming such aggregates as micelles and liposomes for a~lutination studies2. The aglycon portion of ~ycolipids greatly influences the type of aggregates that are formed in aqueous solution; single-chain glycolipids give rise to spherical micelles, whereas double-chain glycolipids form double-layer liposomes 5. In addition, neo-glycolipids would generally show increased stability against enzymic breakdown. Finally, it is desirable to be able to transform (or synthesise) oligosaccharides that are present uniquely on glycoproteins into the corresponding neo-glycolipids for use in receptor studies and coating experiments.