Chemical Synthesis of Oligosaccharides: Efficiency and Selectivity.

Recent Advances in O-Sialylation

“…These derivatives have been widely applied for the synthesis of sialic acid-containing oligosaccharides and glycoconjugates. Several reviews discuss these glycosyl donors. ,,,,− Early results of the application of S -xanthates has also been surveyed .…”

“…A 3-thio moiety provides one of the most reliable auxiliaries and has been studied most extensively among the indirect methods. A detailed discussion or comparison of these methods has not been reported; however, some aspects of this approach have been surveyed. ,,, …”

“…Several reviews discuss these glycosyl donors. 17,18,21,35,[108][109][110][111][112][113] Early results of the application of S-xanthates has also been surveyed. 17 Thioglycosides can be activated under mild conditions in the presence of at least an equimolar amount of a thiophilic promoter.…”

“…A detailed discussion or comparison of these methods has not been reported; however, some aspects of this approach have been surveyed. 31,113,289,290 The first glycosylations with 3-S-phenyl-and 3-Sephenyl-substituted derivatives of Neu5Ac were performed by Ito and Ogawa. [291][292][293] Electrophilic addition of PhSeOAc (generated in situ from PhSeCl and AgOAc) to the double bond of the 2,3-dehydro derivative of Neu5Ac afforded mainly a 2-O-acetyl-3-Sephenyl derivative (3ax/3eq ) 11/1, Scheme 21).…”

A New, Lipophilic p-Alkoxybenzyl Ether Protecting Group and Its Use in the Synthesis of a Disaccharide

“…Despite major advances in the chemical synthesis of oligosaccharides, for example the development of efficient, stereocontrolled glycosylation methods and versatile protecting group schemes, synthesis of higher-membered oligosaccharides remains a challenge in part because of the difficulty of product isolation. In contrast to the chemical advances, the methods of purification of oligosaccharide intermediates are essentially the same as they were decades ago.…”