Thio-oligosaccharides synthesis

Roy R, Andersson EO, Letellier M. Active and latent thio-glycosyl donors in oligosaccharide synthesis. Application to the synthesis of a-sialosides. Tetrahedron Lett. 1992 33 6053-6056. 

SCHEME 14.18 Hindsgaul s solid-phase synthesis of thio-oligosaccharides. 

Hummel, G, Hindsgaul, O, Sohd-phase synthesis of thio-oligosaccharides, Angew. Chem. Lnt. Ed., 38, 1782-1784, 1999. 

Thio-sugars [60,61] are excellent glycosyl donors for oligosaccharide synthesis. Excellent reactivity of activated thioglycosides [62,63] by common promoters such as methyltriflate, dimethyl(methylthio)sulfonium triflate (DMSTS), iodonium dicollidine perchlorate (IDCP), and A-iodosuccininude (NIS) alone or with a combination of triflic acid or silver triflate makes them versatile glycosylation donors. 

To demonstrate further the generality of latent-active glycosyl strategy in oligosaccharide synthesis, the more difficult p(l 3) linkage was next examined (Scheme 11). Glycosylation of latent-disarmed acceptor 54 with ethyl 1 -thio-p-L-fucopyranoside 57 at -30°C in dichloromethane with 4 A MS, promoted by NIS/ TfOH, gave the desired a-(1 3) disaccharide 58 in 83% yield. Under similar... 

Also, thioacetic acid can be used as nucleophile in this approach, to give anomeric thioacetates, which, in a two step-procedure, can be selectively S-deacylated and alkylated to give thioglycosides, a sequence often used in the synthesis of thio-oligosaccharides [25]. 

We have presented an exhaustive and up to date review on the synthesis of thio-oligosaccharides which can be used to probe interactions with proteins. The ease of synthesis of this class of molecule should furnish new tools for glycobiochemists and glycobiologists. 

Fan, L. F. Hindsgaul, O., Synthesis of novel cyclic oligosaccharides beta-l,6-thio-linked cycloglucopyranosides. Org. Lett. 2002,4, 4503-4506. 

Jack bean a-mannosidase has also been able to catalyze the transglycosylation of rhamnose residue. It has been used in the synthesis of a disaccharide Rhaal,2RhaaSEt in 32.1% yield from RhaapNP and ethyl 1-thio-a-D-rhamnopyranoside. The disaccharide product is a derivative of the common oligosaccharide unit of antigenic lipopolysaccharides from Pseudomonas (33). 

Synthesis of Oligosaccharides Having a 5-Thio Sugar Moiety. 71... 

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