The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• glycoside 8 (Scheme 1). Glycosylation is considered as the most crucial step in any oligosaccharide synthesis, although it may be argued that, building block preparations or final deprotection steps remain equally demanding. The main challenge of glycosylation lies in the structural complexity of the

• rigorous planning of one-pot glycosylation the role of a neighbouring group and possible effect of remote participating groups comes into play. One-pot glycosylations have also opened the door of the automated oligosaccharide synthesis which applies the principle of solid-phase synthesis [59][60][61][62

• ] and corresponding automated oligosaccharide synthesis [63][64][65]. These procedures pave the way for the new generation of glycomics and glycochemistry which promises to show new paths towards deciphering the unsolved mysteries of nature [66]. There have been many reviews in literature showcasing the

Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

• Tanmoy Halder and
• Somnath Yadav

Beilstein J. Org. Chem. 2021, 17, 2915–2921, doi:10.3762/bjoc.17.199

• was then deprotected and N-acetylated to finally afford the desired trisaccharide repeating unit as its α-p-methoxyphenyl glycoside. Keywords: capsular polysaccharide; carbohydrate vaccines; O-antigen; oligosaccharide synthesis; one-pot synthesis; Introduction O-antigens or O-specific

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• -protected donors, suitable for iterative oligosaccharide synthesis. The development of these building blocks is showcased to access anomeric 3-aminopropyl- and 1-phosphate free sugars containing this non-native motif. Keywords: alginate; glycosyl 1-phosphate; non-native monosaccharide; tetrazole; uronate

• oligosaccharide synthesis strategy. With such capability effectively demonstrated, we next explored the provision of ᴅ-manno C6-tetrazoles without an orthogonal C4-protecting group. Accordingly, a synthesis initiating from alcohol 15 [19] enabled access to C6-nitrile 16 in three steps (Scheme 4) and an improved

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• resulting from the low stability of amino sugar hemiacetals. The prepared polyfluorinated thiodonors and hemiacetals are valuable intermediates in oligosaccharide synthesis and their utility in glycosylation is currently being studied in our group. Retrosynthetic analysis of the target fluoro analogs

Regioselectivity of glycosylation reactions of galactose acceptors: an experimental and theoretical study

• Enrique A. Del Vigo,
• Carlos A. Stortz and
• Carla Marino

Beilstein J. Org. Chem. 2019, 15, 2982–2989, doi:10.3762/bjoc.15.294

• and one free hydroxy unit in order to achieve glycosylations with respect to the desired regiochemistry. The synthesis of such building blocks is usually the most time-consuming process of oligosaccharide synthesis [2][3]. The knowledge and control of glycosylation regioselectivity of building blocks

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides

• Teresa Mena-Barragán,
• José L. de Paz and
• Pedro M. Nieto

Beilstein J. Org. Chem. 2019, 15, 137–144, doi:10.3762/bjoc.15.14

• substitution pattern of GlcA units for the efficient synthesis of CS oligomers. Keywords: carbohydrate chemistry; chondroitin sulfate; glycosylation; oligosaccharide synthesis; stereoselectivity; Introduction Chondroitin sulfate (CS) is a highly heterogeneous polysaccharide, constituted by the repetition of

Synthesis of α-D-GalpN₃-(1-3)-D-GalpN₃: α- and 3-O-selectivity using 3,4-diol acceptors

• Emil Glibstrup and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2018, 14, 2805–2811, doi:10.3762/bjoc.14.258

• pentasaccharide chain [5][6]. The pioneering work by Paulsen was later followed up by a total synthesis by the Ogawa group [7] and an oligosaccharide synthesis by the Magnusson group [8]. With the increasing understanding of glycobiology, the Forssman antigen has remained an interesting target for vaccine

• finding important for oligosaccharide synthesis. Here we describe this regioselective glycosylation approach in detail. Results and Discussion In the initial strategy for synthesizing the disaccharide, the fully protected acceptor (1 or 2) was intended to be a key building block. However, an unexpected

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

• the hypervalent iodine-mediated oxidative reactions with theses derivatives provide a different method to build glycosidic bonds. Diversity in glycoside bond forming reactions would contribute to improve the oligosaccharide synthesis. Conclusion The Pummerer-type glycosylation includes oxidation of a

• glycoside bond. In the case of nucleoside synthesis, a coupling reaction between a persilylated nucleobase and a sugar donor is typically used [15][16][17]. On the other hand, the reaction between an acceptor and sugar donor is carried out in the presence of an appropriate activator for oligosaccharide

• synthesis [18][19]. In both cases, a Lewis acid is generally used as an activator for sugar donors. Our previous review focused on the development of glycosylation reactions and their application to the synthesis of nucleoside derivatives [17]. In this review, we showed our glycosylation reactions under

Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A

• Aritra Chaudhury,
• Mana Mohan Mukherjee and
• Rina Ghosh

Beilstein J. Org. Chem. 2018, 14, 1095–1102, doi:10.3762/bjoc.14.95

• oligosaccharide synthesis. We have synthesized the aforesaid tetrasaccharide (SPn 6A) based on both stepwise and sequential one-pot glycosylation reactions using easily accessible common building blocks; eventually similar overall yields were obtained in both cases. Keywords: carbohydrates; glycosylation

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• be coupled with another donor and this process is repeated until the desired oligosaccharide structure is assembled. Although many oligosaccharides have been successfully produced through this approach, the traditional oligosaccharide synthesis requires multiple synthetic manipulations on

• . Preactivation-based iterative glycosylation of 2-pyridyl glycosides O-Unprotected 2-pyridyl glycosyl donors have been utilized in oligosaccharide synthesis [29]. The Ye group reported a preactivation protocol using protected 2-pyridyl donors [30]. The preactivation of 2-pyridyl glycoside 14 was performed using

• 4-(benzenesulfinyl)morpholine (BSM)/Tf2O [53]. The combination of BSP/Tf2O [19][49] has been utilized as the promoter for iterative oligosaccharide synthesis including oligoglucosamine library [20], oligomannan [54] and Lewisa trisaccharide [55]. During their synthesis, van der Marel and co-workers

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

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

• -glycosylation” by Valverde et al. [54], “remote glycosidation” by Takahashi [55] and “templated oligosaccharide synthesis” by Demchenko [56]. Initially introduced by Kusumoto et al. in 1986 [46], the molecular clamping clearly demonstrated the advantages that intramolecular glycosylations can offer. The first

• debenzylation followed by global acetylation to afford product 30. The extension of this approach to convergent oligosaccharide synthesis and reiterative sequencing in presented in Scheme 8. Thus, maltose and lactose disaccharide building blocks were linked via the xylylene tether, and the resulting compound 31

• freedom and also to form smaller ring sizes [81]. Templated oligosaccharide synthesis Recently, Demchenko and co-workers introduced templated oligosaccharide synthesis, wherein bisphenol A (BPA) was used as the template and succinoyl, glutaryl or phthaloyl linkers were used to tether glycosyl donors and

1,3-Dibromo-5,5-dimethylhydantoin as promoter for glycosylations using thioglycosides

• Fei-Fei Xu,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2017, 13, 1994–1998, doi:10.3762/bjoc.13.195

• agents that are commonly used in oligosaccharide synthesis due to their accessibility, stability, compatibility with various reaction conditions, and orthogonality to other donors [1][2][3][4][5]. Different electrophilic/thiophilic reagents have been developed as promoters to activate thioglycoside

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• specific protecting and/or activating groups and the fine control of the resulting anomeric linkage, thus leading now to i) a huge repertoire of stereoselective methods for glycosylation reactions [3] and ii) the premise of few automated oligosaccharide synthesis [4], such glycosylation process still

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

• furanosides. These may find application as enzyme substrates and possibly as inhibitors in several bacterial diseases, as well as in solid-phase-oligosaccharide synthesis, as shown. However, the main drawback is still the multistep synthesis of these anomeric activating donors. 3.2 Self-activation of the

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

• Adesh Kumar Singh,
• Varsha Tiwari,
• Kunj Bihari Mishra,
• Surabhi Gupta and
• Jeyakumar Kandasamy

Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113

• role in carbohydrate synthesis. Thioglycosides, glycosyl sulfoxides and sulfones have been widely used as glycosyl donors in oligosaccharide synthesis which can be activated under mild reaction conditions [5][6][7][8][9][10]. Glycosyl sulfoxide donors usually provide excellent anomeric selectivity

• during the synthesis of various glycosyl linkages not only in solution phase but also in solid-phase oligosaccharide synthesis [6][7][8][9][11]. Glycosyl sulfones were also used as donors in the preparation of various C- and O- linked oligosaccharides and functionalized glycols [8][9][12]. In addition

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• provide an alternative orthogonal protective group to the more conventional acetyl, benzoyl and benzyl groups. Particularly in oligosaccharide synthesis where many orthogonal hydroxy protective groups are required silicon protective groups have frequently been introduced in both glycosyl donors and

Synthesis and NMR studies of malonyl-linked glycoconjugates of N-(2-aminoethyl)glycine. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger,
• Sven Hafner and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 1939–1948, doi:10.3762/bjoc.12.183

• , on the other hand, may provide sufficient amounts of pure material for such studies. Despite the great achievements in oligosaccharide synthesis during the past decades, the preparation of complex oligosaccharides can be tedious, lengthy or circuitous, and the often intrinsic intricacy of a chemical

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• exclusively when the secondary hydroxyl glucoside 24 was used (Table 4, entry 13). Notably, the disubstituted side product was not observed in this reaction. On the basis of these results, we demonstrated the applicability of the methodology in oligosaccharide synthesis by synthesising trisaccharide 66 in two

Galactan synthesis in a single step via oligomerization of monosaccharides

• Marius Dräger and
• Amit Basu

Beilstein J. Org. Chem. 2014, 10, 2658–2663, doi:10.3762/bjoc.10.279

• . Additionally, numerous other steps involving protecting group removal and installation are required to assure regio- and stereoselective glycan assembly. One-pot strategies for oligosaccharide synthesis can streamline the process by sequential iterative glycosylations, without the need for work-up and

• have interesting materials properties, it does not provide discrete compounds and is not useful for targeted oligosaccharide synthesis. In contrast, there are several cases where the product mixture of an oligomerization reaction has been separated into discrete oligosaccharides of varying lengths. An

• here is a highly efficient method for homo-oligosaccharide synthesis. We are currently investigating the extension of this approach to targets other than galactans and to the assembly of glycans linked via secondary hydroxy groups. Pyrenebutanol (3) initiated oligomerization. Scope of oligomerization

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2014, 10, 2453–2460, doi:10.3762/bjoc.10.256

• difficult due to the micro heterogenity of naturally occurring saccharides. For this reason chemical oligosaccharide synthesis is the only alternative for providing sufficient amounts of pure material for detailed biological studies. However, the synthetic preparation of complex oligosaccharides is still

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• -rhamno-trisaccharide; deoxygenation on thioglycoside; multivalent glycosystems; one-pot sequential glycosylation; Pseudomonas aeruginosa; Introduction With the firm establishment of the critical roles played by oligosaccharides in diverse biological processes [1][2][3][4], the field of oligosaccharide

• synthesis has seen a rapid development over the last two decades [5][6][7]. The D-rhamnoside motif is of particular interest with its presence established in the LPS/EPS systems of various bacterial strains which are pathogenic towards both plants and animals. These species include the Burkholderia cepacia

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• . Keywords: glycosylation; mucin-type oligosaccharides; O-glycans; oligosaccharide synthesis; Introduction Mucins are heavily glycosylated glycoproteins that may be membrane-associated or secreted in gel form and play an important biological role in the respiratory and intestinal tracks [1][2][3]. Mucins

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• cleavage efficiencies on these functionalized solid supports were investigated, and restrictions for the choice of solid support for oligosaccharide synthesis were found. Keywords: glycosylation; hydrogenolysis; linkers; oligosaccharides; resins; solid-phase synthesis; Findings Since Bruce Merrifield

• ][22][23]. It was early on recognized that the linker plays a pivotal role for oligosaccharide synthesis, as its chemical properties determine the conditions that can be used for glycosylation and deprotection reactions [7][20][23][24][25]. Equally important is the choice of solid support and many

• different resins were briefly explored [26]. However, for automated solid-phase oligosaccharide synthesis, Merrifield polystyrene resin has almost exclusively been used as the solid support. Here, we describe the development of a new linker system that was tested in the context of different solid supports

Acylsulfonamide safety-catch linker: promise and limitations for solid–phase oligosaccharide synthesis

• Jian Yin,
• Steffen Eller,
• Mayeul Collot and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 2067–2071, doi:10.3762/bjoc.8.232

• Abstract Safety-catch linkers are useful for solid-phase oligosaccharide synthesis as they are orthogonal to many common protective groups. A new acylsulfonamide safety-catch linker was designed, synthesized and employed during glycosylations using an automated carbohydrate synthesizer. The analysis of the

• cleavage products revealed shortcomings for oligosaccharide synthesis. Keywords: glycosaminoglycans (GAGs); glycosylation; resins; safety-catch linker; solid-phase synthesis; Findings Solid-phase oligosaccharide synthesis [1][2] has been automated [3][4][5] to rapidly assemble complex oligosaccharides

• . Key to the success of solid-phase syntheses is the linker that connects the first carbohydrate building block to the solid support [6]. This linker has to remain stable throughout oligosaccharide synthesis but must be cleaved at the end of the reaction sequence to release the oligosaccharide and

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• external partners such as cells and viruses. Straightforward access to sialosides is required in order to study their biological functions on a molecular level. Here, automated oligosaccharide synthesis was used to facilitate the preparation of this class of biomolecules. Our strategy relies on novel

• diverse set of glycans rapidly and efficiently. The automated synthesizer proved capable of performing iterative glycosylation–deprotection cycles under conditions commonly employed for solution-phase oligosaccharide synthesis. The synthetic strategy relies on the solid support-bound linker 17 (Scheme 3