Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• and yields. Hence, intramolecular glycosylations have a particular relevance to special cases of glycosylation or particularly challenging targets, such as 1,2-cis glycosides, where other, more direct methods fail to provide acceptable results. Presented herein is an overview of methods that have been

• introduced by Schmidt [68], was successfully applied to the intramolecular synthesis of 1,2-cis glycosides with complete selectivity (Scheme 7) [69]. Thus, thioglycoside 25 is first alkylated at C-3 position. The resulting intermediate 26 is then used as the alkylating reagent to create a tether to acceptor

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• position which could provide under the right conditions, regioselectively and stereoselectively 1,2-cis glycosides of a wide variety. The substrate scope is broad and even includes glycosyl phosphates and esters in addition to a host of alcohol acceptors (Scheme 8). Certainly the most important application

• of this chemistry is its ability to provide 1,2-cis glycosides with good stereoselectivity, as these glycosides still remain among the most challenging stereoisomers to synthesize as C2 neighboring group participation is not possible [40]. In fact, the access to 1,2-cis glycosides is considered a

• alcohols (Scheme 31). In a second two-step process [91], the Shoda group designed another catalytic system that provided 1,2-cis glycosides in very high yield and often perfect stereoselectivity. In the first step of the reaction the anomeric position is activated by using a dehydrative condensing agent 4

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• glycolipids [35][36][37]. Sulfated sugars are isomerized from pyranosides to furanosides [38]. The anomerization reaction would be a useful methodology to prepare 1,2-cis-glycosides such as heparin and glycosylphosphatidylinositol (GPI) anchors. Structure of mycothiol 1. Detoxification pathway mediated by MSH

Benzyne arylation of oxathiane glycosyl donors

• Martin A. Fascione and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2010, 6, No. 19, doi:10.3762/bjoc.6.19

• sulfur arylation, glycosylation of acetate ions proceeded with high levels of stereoselectivity to afford α-glycosyl acetates in a ‘one-pot’ reaction, even in the presence of alternative acceptor alcohols. Keywords: benzyne; 1,2-cis-glycosides; glycosyl acetates; oxathiane glycosyl donors

• , carbohydrate chemists must overcome the myriad challenges presented by their complex synthesis. The most important challenge is control over the stereoselectivity of reactions at the anomeric centre; in particular for the stereoselective synthesis of 1,2-cis-glycosides [9]. This area has been the subject of

• then already pre-organised to give a 1,2-cis directing group upon activation, and afford 1,2-cis-glycosides 7 on alcohol addition. Following the synthesis of the oxathiane ketal glycosyl donors 5, activation of the β-thioglycoside linkage was necessary to form the key trans-decalin sulfonium ion 6, and