Chemical syntheses of inulin and levan structures.
A fructofuranosyl thiglycoside donor, ethyl 6-O-acetyl-3-O-benzyl-1,4-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-2-thio-beta-D-fructofuranoside (11), designed to yield stereospecifically beta-linkages and also to allow subsequent elongation in the 6- and/or 1-positions, was prepared and used in syntheses of levan and inulin structures. DMTST-promoted glycosylation between 11 (1.3 mol equiv) and methyl beta-D-fructofuranoside 6-OH and 1-OH acceptors (3 and 6) gave stereospecifically the protected methyl levanobioside 12 and inulinobioside 17 in excellent yields (80 and 86%), respectively. Protecting group manipulations on these afforded new disaccharide 6'-OH and 1'-OH acceptors (13 and 19), which were coupled again with donor 11 (1.0 mol equiv) to yield methyl levanotrioside 14 and inulinotrioside 20 in high yields, 65 and 67%, respectively. These were transformed into new acceptors and also fully deprotected to afford the methyl glycosides of levanotriose and inulinotriose, all structures that have earlier not been accessible by chemical synthesis.
Oscarson
Stefan
S
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden. s.oscarson@organ.su.se
Sehgelmeble
Fernando W
FW
D002240:Carbohydrate Sequence; D002625:Chemistry, Organic / Q000379:methods; D005630:Fructans / Q000138:chemical synthesis*; D005632:Fructose / Q000031:analogs & derivatives / Q000138:chemical synthesis; D006031:Glycosylation; D007444:Inulin / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000032:analysis / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D005630:Fructans; D009844:Oligosaccharides; D005632:Fructose; D007444:Inulin; C072599:levan