Syntheses of the title glycosides are described. The critical O-glycosylations were carried out in the presence of boron trifluoride etherate with a high degree of alpha-selectivity.
Synthesis of allyl and benzyl 4-O-(3,6-di-O-methyl-β-d-glucopyranosyl)-2,3-di-O-methyl-α-l-rhamnopyranoside
✍ Scribed by Jose R. Mariño-Albernas; Vicente Verez-Bencomo; Leandro Gonzalez; Carlos S. Perez
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 803 KB
- Volume
- 165
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
Condensation of 2,4-di-O-acetyl-3,6-di-O-methyl-a-~glucopyranosyl bromide with either ally1 or benxyl2,4-di-0-methyl-cu+rhamnopyranoside in the presence of mercuric cyanide, followed by 0-deacetylation, gave the title oligosaccharides in excellent yields.
📜 SIMILAR VOLUMES
The title branched-trisaccharide derivatives (9 and 13) have been synthesised from methyl 2,3-O-(2-nitrobenzylidene)-a-L-rhamnopyranoside (2) using the 2nitrobenzylidene residue as a temporary blocking-group. Condensation of 2 with methyl (2,3,4-tri-O-acetyl-a-D-glucopyranosyl bromide)uronate afford
D-Ribose was converted into methyl 5-O-benzyl-beta-D-ribofuranoside and this, on tin-mediated allylation, gave a mixture of the 2-O-allyl and 3-O-allyl derivatives which were separated by chromatography. The more polar isomer was characterised as the 3-O-allyl derivative after conversion via 3-O-all
Allyl 4-O-benzyl-~-L-rhamnopyranoside was converted into allyl 4-O-benzyl-3-O-methyl-oeL-rhamnopyranoside and this was condensed with 2,3,4-tri-O-acetyl-~-L-rhamnopyranosyl chloride to give a disaccharide derivative which was converted into allyl 4 This disaccharide derivative was condensed with 2,
The title trisaccharide glycosides were needed for studies of the interactions of &tins, receptor sites for bacteriophages with Salmonella lipopolysaccharide corespecificity, and correlation of n.m.r. chemical shifts and structure. The methods used in the syntheses were conventional. Thus, 2,3,4,6-