- Investigating cellular metabolism of synthetic azidosugars with the Staudinger ligation
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The structure of sialic acid on living cells can be modulated by metabolism of unnatural biosynthetic precursors. Here we investigate the conversion of a panel of azide-functionalized mannosamine and glucosamine derivatives into cell-surface sialosides. A key tool in this study is the Staudinger ligation, a highly selective reaction between modified triarylphosphines and azides that produces an amide-linked product. A preliminary study of the mechanism of this reaction, and refined conditions for its in vivo execution, are reported. The reaction provided a means to label the glycoconjugate-bound azidosugars with biochemical probes. Finally, we demonstrate that the cell-surface Staudinger ligation is compatible with hydrazone formation from metabolically introduced ketones. These two strategies provide a means to selectively modify cell-surface glycans with exogenous probes.
- Saxon, Eliana,Luchansky, Sarah J.,Hang, Howard C.,Yu, Chong,Lee, Sandy C.,Bertozzi, Carolyn R.
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p. 14893 - 14902
(2007/10/03)
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- ERPROBTE SYNTHESE VON 2-AZIDO-2-DESOXY-D-MANNOSE UND 2-AZIDO-2-DESOXY-D-MANNURONSAEURE ALS BAUSTEIN ZUM AUFBAU VON BAKTERIEN-POLYSACCHARID-SEQUENZEN
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The azidonitration of 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol at low temperature afforded preponderantly the azidonitrate having the D-manno configuration.After reaction with sodium acetate, 1,3,4,6-tetra-O-acetyl-2-azido-2-deoxy-α-D-mannopyranose was directly isolated and deblocking gave 2-azido-2-deoxy-D-mannopyranose. 3,4,6-Tri-O-acetyl-2-azido-2-deoxy-α-D-mannopyranosyl bromide and 2-azido-3,4,6-tri-O-benzyl-α-D-mannopyranosyl bromide were prepared and are suitable for selective α- and β-glycoside synthesis.In the presence of platinum-oxygen, the catalytic oxidation of benzyl 2-azido-2-deoxy-α-D-mannopyranoside gave in high yields (benzyl 2-azido-2-deoxy-α-D-mannopyranosid)uronic acid from which 2-amino-2-deoxy-D-mannopyranuronic acid was obtained.By catalytic oxidation, selectively blocked derivatives of 2-amino-2-deoxy-D-mannopyranose were converted into the correspondind uronic acid derivatives.
- Paulsen, Hans,Lorentzen, Jens Peter,Kutschker, Wolfram
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p. 153 - 176
(2007/10/02)
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- ADDITION OF HALOGENOAZIDES TO GLYCALS
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Addition of chloroazide to 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-lyxo- (1) and -D-arabino-hex-1-enitol (2) under u.v. irradiation proceeds regio- and stereo-selectively yielding mainly O-acetyl derivatives of 2-azido-2-deoxy-D-galactopyranose and -D-glucopyranose, respectively. 3,4,6-Tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosyl azide and 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-talopyranose (from 1), and 1,3,4,6-tetra-O-acetyl-2-chloro-2-deoxy-α-D-glucopyranosyl azide and 1,3,4,6-tetra-O-acetyl-2-azido-2-deoxy-α-D-mannopyranose (from 2) are byproducts. 1,5-Anhydro-3,4,6-tri-O-benzyl-2-deoxy-D-lyxo- and -D-arabino-hex-1-enitol reacted more rapidly with chloroazide, to give, under irradiation, derivatives of 2-azido-2-deoxy-D-galactose and -D-glucose, respectively.However, reaction in the dark gave mainly O-benzyl derivatives of 2-chloro-2-deoxy-α-D-galacto- and -α-D-glucopyranosyl azide.The difference between the products obtained may depend on the existence of two parallel processes, one radical (under irradiation), and the other ionic (reaction in the dark).
- Bovin, Nicolai V.,Zurabyan, Sergei E.,Khorlin, Anatoly Y.
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