Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• linear iterative [263] approaches were reported. A block coupling approach enabled access to a collection of free amino or N-acetylated structures up to 11mer [264]. Intramolecular glycosylation between a thioglycoside and a free C-6 hydroxy group at the non-reducing end enabled the synthesis of β(1–6

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• 178 and 179 were considered to have self-assembled structures versatile for the synthesis of serenylated and threonylated glycosides by intramolecular glycosylation. In addition, the access to 2-deoxyglycosides should be easily achievable by subsequent radical deiodination of the products. After

• several experiments, treatment with a catalytic amount of TMSOTf was found to be suitable for the intramolecular glycosylation, giving the corresponding acid, which was easily converted to the corresponding methyl ester 180 under EDCI/DMAP/MeOH conditions [85]. Similarly, the reaction of the threonine

• ester glycosides were considered to have self-assembled structures suitable for intramolecular glycosylation. As depicted in Figure 9, treatment of 184 with TMSOTf first cleaved the silyl ether to form 185, which was correctly positioned to undergo intramolecular glycosidation. As a result, the Lewis

Synthetic and semi-synthetic approaches to unprotected N-glycan oxazolines

• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 416–429, doi:10.3762/bjoc.14.30

• ‘difficult’ Manβ(1–4)GlcNAc linkage, including a variety of methods of intramolecular glycosylation [63][64][65][66][67][68][69][70][71] the most widely applied has been the Crich direct β-mannosylation [72][73][74][75][76]. However, one apparent limitation is that generally the reaction only works well if

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

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

• other, more fundamental factors and aspects of glycosylation. Extensive studies dedicated to conformation, configuration, stereoelectronics of the starting material, and key reaction intermediates have emerged [34][35][36][37]. Beside these attempts, an area of the intramolecular glycosylation has also

• [45] are often credited for the invention of the intramolecular glycosylation in 1991. However, it is a pioneering albeit less known research by Kusumoto et al. in 1986 [46] that actually started the developments in this area. Of this general idea for the intramolecular glycosylation, three different

• ][40] and IAD in particular [41][48][49][50]. Review Molecular clamping method Early developments The “molecular clamp” concept (approach A, Figure 1) represents the first general concept for a intramolecular glycosylation strategy. The attachment of the glycosyl donor and acceptor via a tether takes

Dependency of the regio- and stereoselectivity of intramolecular, ring-closing glycosylations upon the ring size

• Patrick Claude,
• Christian Lehmann and
• Thomas Ziegler

Beilstein J. Org. Chem. 2011, 7, 1609–1619, doi:10.3762/bjoc.7.189

• glucosyl moieties was mainly responsible for the observed regioselectivity and anomeric selectivity of the ring-closing glycosylation step. Keywords: intramolecular glycosylation; molecular modeling; prearranged glycosides; Introduction Intramolecular O-glycosidic bond formation of tethered glycosyl

• concept”, the sole true intramolecular glycosylation approach which was developed in our [18][19][20] and Valverde’s group [21], glycosyl donor and acceptor are linked by a stable tether attached to positions not directly involved in the glycosylation step. Upon activation of the leaving group, an

• intramolecular, ring-closing condensation occurs affording a tethered saccharide (Figure 1). Despite the fact that the “prearranged-glycoside concept” for intramolecular glycosylation has been successfully applied to the construction of glycosidic bonds that are otherwise difficult to establish (i.e., β-D