Extended applications and potential limitations of ring-fused 2,3-oxazolidinone thioglycosides in glycoconjugate synthesis

Stereocontrolled 1,2-cis glycosylation as the driving force of progress in synthetic carbohydrate chemistry

“…76 Although high α-selectivity could be obtained, the oxazolidinone protected donor showed propensity to undergo side reactions, such as N -glycosylation or N -sulfenylation. To rectify this, Kerns et al .…”

“…78 reported the use of N -acetylated oxazolidinones. 76a,77a These donors showed switchable stereoselectivity in glycosylation that was achieved by tuning the reaction conditions. 79 This interesting finding stimulated further studies.…”

Recent trends in the synthesis of O-glycosides of 2-amino-2-deoxysugars

“…346 The 2,3-N,O-carbamate protecting group 347 was investigated in glycosylation reactions by Kerns and co-workers. 317,348 Their approach to the synthesis of this bicyclic derivative involved sequential thioglycosylation with PhSH and transformation of the acetamido moiety in 129 into 2-N-benzyloxycarbonylacetamido derivative, which was globally deprotected in two steps to afford 130 (Scheme 24). The cyclocarbamate moiety was then introduced using p-nitrophenylchloroformate; subsequent O-acetylation led to the glycosyl donor 131.…”

Development of Novel Glycosyl Donors for 1,2-<i>cis</i> Glycosylation Reaction for Amino Sugar and Synthesis of anti-<i>Helicobacter pylori</i> Oligosaccharide

“…Subsequent reports, however, describe the drawbacks of such trans-carbamate donors (11)(12)(13), including signiˆcant side reactions such as the sulfenylation from PhSOTf and glycosylation at the nitrogen atom (Scheme 2). To avoid such side reactions, the nitrogen atom was protected as an acetimide-unfortunately, the stereoselectivity was signiˆcantly reduced, and in some cases, the reaction generated undesired bglycoside 17b as a major isomer.…”