Intramolecular glycosylation

Abstract

Carbohydrate oligomers remain challenging targets for chemists due to the requirement for elaborate protecting and leaving group manipulations, functionalization, tedious purification, and sophisticated characterization. Achieving high stereocontrol in glycosylation reactions is arguably the major hurdle that chemists experience. This review article overviews methods for intramolecular glycosylation reactions wherein the facial stereoselectivity is achieved by tethering of the glycosyl donor and acceptor counterparts.

Macrolide Core Synthesis of Calysolin IX Using an Intramolecular Glycosylation Approach

“…Achieving high efficiency and stereocontrol in glycosylation reactions is arguably still the major effort in the synthesis of widely distributed carbohydrate‐containing oligomers . While the intermolecular formation of glycosidic bonds has reached a satisfactory level of development, the intramolecular glycosylation strategy is still not broadly used and accepted in the synthesis . As a result, construction of the macrocyclic rings by means of glycosylation is not seen as an efficient tool in the synthesis of macrocyclic compounds and therefore practically neglected in the literature .…”

Total synthesis, isolation, surfactant properties, and biological evaluation of ananatosides and related macrodilactone-containing rhamnolipids

“… 39–41 Alternatively, capitalizing on glycosylation chemistry, 42,43 carbohydrate-embedded macrolactones can be built upon stereoselective intramolecular glycosylation using the ester-linked β-hydroxylipid as a stereodirecting tether. 44 Importantly, the latter approach has only been implemented in rare occasions for the total synthesis of macrolactone-containing natural products. 29 …”

“…The β-selectivity would also be favored by the steric constraint exerted by the resulting macrolide. 44 The propensity of the AZMB group to be orthogonally cleaved by means of, for instance, Staudinger reduction 36,47 without affecting the macrolide functionality represents a further advantage of using this protecting group at this specific position. Precursor 7 would be readily synthesized by Steglich esterification 48 between thioglucoside 9 and dilipid 10 .…”

Automated Chemical Oligosaccharide Synthesis: Novel Approach to Traditional Challenges

“…A better stereocontrol is achieved by tethering the reaction counterparts and restricting the glycosyl acceptor attack. 311–318 The best known example, intramolecular aglycone delivery (IAD), was introduced by Barresi and Hindsgaul. 319 Over the years, IAD has evolved into a powerful means to perform glycosylations of complex targets with high efficiency and yields.…”