186831-49-2

Upstream product

• 186831-38-9 2,3,4-tri-O-acetyl-6-deoxy-α-L-talopyranosyl chloride 
• 186831-45-8 Acetic acid (2S,3R,4R,5S)-5-((S)-1-acetoxy-ethyl)-4-benzyloxy-3-((2S,3R,4R,5R,6S)-3,4,5-triacetoxy-6-methyl-tetrahydro-pyran-2-yloxy)-tetrahydro-furan-2-yl ester 
• 143394-72-3 1,2,3,4-tetra-O-acetyl-6-deoxy-α-L-talopyranose 
• 143332-42-7 2,3,4-O-triacetyl-6-deoxy-α-L-talose 

Downstream Products

• 186831-59-4 (2R,4R,5R,6S)-5-[(2R,3R,4R,5S)-5-((S)-1-Acetoxy-ethyl)-4-benzyloxy-3-((2S,3R,4R,5R,6S)-3,4,5-triacetoxy-6-methyl-tetrahydro-pyran-2-yloxy)-tetrahydro-furan-2-yloxy]-4-benzyloxy-2-methoxy-tetrahydro-pyran-2,6-dicarboxylic acid dimethyl ester 

Relevant academic research and scientific papers

Synthesis of the unique trisaccharide repeating unit, isolated from lipopolysaccharides Rhizobium leguminosarum bv. trifolii 24, and its analogue

The synthesis of trisaccharide: 6-d-α-L-Talp(1→2)-α-L-Rhap(l →5)- DHA, and its analogue: 6-d-α-L-Talp(1→2)-β-L-Rhaf(1→5)DHA is described. In the first step a disaccharide, composed of 6-d-L-Talp and L-Rhap was obtained. This, in turn, was converted to the corresponding 1- trichloroacetimidate and coupled with DHA alcohol to afford the required trisaccharide. Its analogue was achieved by the conversion of the above disaccharide to the glycosyl bromide, involving the rhamnopyranose ring scission, followed by condensation with DHA in Koenigs-Knorr procedure.

Synthesis of the Unique Trisaccharide: 6-d-L-Talpα(1->2)-L-Rhafβ(1->5)-DHA

Preparation of the title trisaccharide resulted from two remarkable facts: 1) during acetolysis of the anomeric t-butyl group in the fully protected disaccharide 4, the rhamnopyranoside ring underwent an unusual conversion into the furanose form to furnish 5a; 2) stereoselective coupling of 5-O-acetyl-3-O-benzyl-2-O-(2,3,4-tri-O-acetyl-6-deoxy-α-L-talopyranosyl)-α-L-rhamnofuranosyl bromide (5b) with the glycosyl acceptor 7b formed surprisingly the β-linkage, to give the corresponding trisaccharide 8a.