Synthesis of methyl glycosides of β-(1→6)-linked
-galactobiose, galactotriose, and galactotetraose having a 3-deoxy-3-fluoro-β-
-galactopyranoside end-residue |
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Authors: | Pavol Kov Cornelis P J Glaudemans |
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Institution: | Pavol Ková,Cornelis P. J. Glaudemans |
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Abstract: | Methyl 2,4-di-O-acetyl-3-deoxy-3-fluoro-β-
-galactopyranoside was synthesized by sequential tritylation, acetylation, and detritylation of methyl 3-deoxy-3-fluoro-β-
-galactopyranoside, and used as the initial nucleophile in the synthesis of methyl β-glycosides of (1→6)-β-
-galacto-biose, -triose (20), and -tetraose (22) having a 3-deoxy-3-fluoro-β-
-galactopyranoside end-residue. The extension of the oligosaccharide chais, to form the internal units in 20 and 22, was achieved by use of 2,3,4-tri-O-acetyl-6-O-bromoacetyl-α-
-galactopyranosyl bromide as a glycosyl donor, and mercuric cyanide or silver triflate as the promotor. While fewer by-products were formed in the reactions involving mercuric cyanide, the reactions catalyzed by silver triflate were stereospecific and yielded only the desired β (trans) products. |
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