Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• , Russian Federation 10.3762/bjoc.20.18 Abstract The development of new methods for chemical glycosylation commonly includes comparison of various glycosyl donors. An attempted comparison of chemical properties of two sialic acid-based thioglycoside glycosyl donors, differing only in the substituent at O-9

• inevitably change. This could lead to modifications of the structure of the corresponding supramers of reactants, hence their properties. Indeed, we have already addressed this issue and found that the stereoselectivity of the glycosylation of alcohol 3 by a related N,O-acetylsialyl thioglycoside may depend

• procedure The glycosylation procedure followed that described in our previous publications [33][36][37]. A mixture of thioglycoside sialyl donor 1 [36] or 2 (1 equiv, 0.1 or 0.15 mmol) and alcohol 3 [54] (1 equiv) was dried in vacuo for 2 h, then anhydrous MeCN (2.0 mL for 0.1 mmol of sialyl donor and 1.0

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• TEG-N3 spacer attached is described. The synthesis of the TF antigen comprises seven steps, from a known N-Troc-protected galactosamine donor, with an overall yield of 31%. Both the spacer (85%) and the galactose moiety (79%) were introduced using thioglycoside donors in NIS/AgOTf-promoted

• glycosylation reactions. The 3’-sulfate was finally introduced through tin activation in benzene/DMF followed by treatment with a sulfur trioxide–trimethylamine complex in a 66% yield. Keywords: regioselective sulfation; thioglycoside donors; Thomsen–Friedenreich antigen; Introduction In a collaboration

• -linked TEG-spacer glycosides with per-acetylated lactose and 2-phthalimidoglucosamine [1][2] worked well with 2-chloroethanol as a spacer (68%, pure α) but failed with the TEG-Cl spacer [12], why we instead decided to use a thioglycoside donor to introduce the spacer. To ensure α-selectivity a di-tert

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• , syntheses of C6-modified mannose 1-phosphates 13 and 17 were developed (Scheme 1). The synthesis of 6-amino-6-deoxymannose 1-phosphate 13 started from protected thioglycoside 10 [6]. A two-step modification using Appel halogenation followed by nucleophilic substitution with azide furnished 11. Conversion of

• the intermediate C6–bromide to 11 was confirmed by 13C NMR, with C6 shifting downfield from δC 33.4 ppm to 51.6 ppm. Following this, dibenzyl phosphate was glycosylated with 11 using NIS/AgOTf activation of the thioglycoside, which proceeded in good yield (65%) to deliver 12. A final global

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

• Md Azadur Rahman,
• Kana Kuroda,
• Hirofumi Endo,
• Norihiko Sasaki,
• Tomoaki Hamada,
• Hiraku Sakai and
• Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

• our study with the optimization of the arylthio group of thioglycoside 1, carrying an unprotected 4-OH group, an acetyl-protected 3-OH unit, a benzyl-protected 6-OH group, and a phthaloyl-protected 2-NH2 unit (Figure 2) [3]. Electrochemical polyglycosylation was performed by a sequential two-step

• process, which involved anodic oxidation at −80 °C and glycosylation at −50 °C. The crude product of the reaction was purified by gel permeation chromatography (GPC), and the monosaccharides 1a–d and oligosaccharides 2a–d (n = 2)–7a–d (n = 7) were isolated. Only thioglycoside 1a (Ar = 4-FC6H4, Eox = 1.70

• V vs SCE) gave oligosaccharides up to hexasaccharide 6a, although the yield of pentasaccharide 5a (3%) and hexasaccharide 6a (1%) was very low. For thioglycoside 1b (Ar = 4-ClC6H4, Eox = 1.68 V vs SCE), the highest conversion (79%) and the highest yield of tetrasaccharide 4b (14%) were observed

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

• described in Scheme 2. With the monosaccharide building blocks in hand, the galactosamine donor 6 was coupled with galactose acceptor 7 by activation of the thioglycoside using N-iodosuccinimide (NIS) in the presence of TMSOTf to afford the desired disaccharide β-ᴅ-GalpNHTroc-(1→4)-α-ᴅ-Galp (4) in 85% yield

• . Initial studies using the thioglycoside donor 3 were not very fruitful, affording a complex mixture of products. Therefore, we modified our strategy to include its trichloroacetimidate derivative as the donor. The thioglycoside 3 was converted to the anomeric hydroxide using trichloroisocyanuric acid

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

• . Peracetylated thioglycoside donors 52 were reacted with 4-methylbenzoylated (MBz) acceptors 53, following NIS/AgOTf activation (Scheme 7C). Upon global deprotection, a collection of well-defined oligoxylans with 4–10 monosaccharide units was obtained [205]. A convergent approach was also employed to prepare a β

• control over size and substitution pattern. Classical methods include chitinase-catalyzed assembly via ring-opening polyaddition of N,N’-diacetylchitobiose oxazoline derivatives [237][238][239] or self-condensation of N-phthalimide protected thioglycoside [240]. Enzymatic polymerization promoted by

• glycosylation strategy was developed to alternately stitch N-Phth-protected thioglycoside donors and N-Phth-protected fluoride donors to obtain COS up to 7mer (Scheme 10) [253]. Similarly, trichloroacetimidate and thioglycoside donors permitted the synthesis of short COS [254]. Upon assembly, the N-Phth PGs

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

• to explore the synthesis of a ᴅ-manno C6-tetrazole thioglycoside donor and examine subsequent installation of C1 phosphate and anomeric linker groups. Results and Discussion An initial route towards a protected C6-tetrazole building block started from known mannuronic acid thioglycoside 1 (Scheme 1

• yield of 50% (compared to 31% in accessing 9 from 7). Nitrile 16 then underwent dipolar cycloaddition with NaN3, converting it to C6-tetrazole thioglycoside 17 in 55% yield. This material was then protected at tetrazole nitrogen in 76% yield using PMBCl to give 18 and 19 (N1-PMB/N2-PMB = 1:1.2) as

• appropriate chemoenzymatic syntheses [21][22][23]. Conclusion We have established synthetic access to a series of C6-tetrazole thioglycoside monosaccharide building blocks with capability for orthogonal C4- and tetrazole N-protecting groups. We demonstrate anomeric manipulation of these donors to new

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

• thioglycosides prepared from deoxyfluorinated 1,6-anhydro-2-azido-β-ᴅ-hexopyranose precursors by ring-opening reaction with phenyl trimethylsilyl sulfide. Nucleophilic deoxyfluorination at C4 and C6 by reaction with DAST, thioglycoside hydrolysis and azide/acetamide transformation completed the synthesis

• coordination of ZnI2. When the α-anomer of thioglycoside 17 was separately subjected to the reaction conditions, the byproduct 20 started to form in trace amounts in accordance with the suggested mechanism. The ring contraction may involve formation of a transient oxiranium cation as suggested in Scheme 2 [42

• ). 4,6-O-Benzylidenation of diol 18 followed by regioselective opening of the benzylidene acetal produced compound 35. Subsequent DAST deoxyfluorination delivered the desired thioglycoside 36 (Scheme 3). For both compounds 18 and 35, deoxyfluorination of the C4 hydroxy group occurred with inversion of

Synthesis of the tetrasaccharide repeating unit of the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71^T using linear and one-pot iterative glycosylations

• Arin Gucchait,
• Pradip Shit and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 1700–1705, doi:10.3762/bjoc.16.141

• glycosylations followed by in situ removal of the PMB group in one pot. The stereochemical outcome of the newly formed glycosidic linkages was excellent using thioglycoside derivatives as glycosyl donors and a combination of N-iodosuccinimide (NIS) and perchloric acid supported on silica (HClO4-SiO2) as the

• elongation C-3 hydroxy group in the ʟ-rhamnosyl thioglycoside donor 3 allowed carrying out the stereoselective glycosylation steps followed by the removal of the PMB group [25] in one pot. This was achieved by using a combination [26][27][28][29][30] of N-iodosuccinimide (NIS) and perchloric acid supported

• repeating unit of the polysaccharide (Figure 1). The stereoselective glycosylation of compound 2 with ʟ-rhamnosyl thioglycoside 3 in the presence of a combination of NIS and HClO4-SiO2 [26][27] followed by removal of the PMB group [25] from the product in the same pot by tuning of the reaction conditions

Synthesis of Streptococcus pneumoniae serotype 9V oligosaccharide antigens

• Sharavathi G. Parameswarappa,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2020, 16, 1693–1699, doi:10.3762/bjoc.16.140

• trisaccharide will be prepared from five differentially protected building blocks (8–12) that will ensure the desired stereochemical outcome during the glycosylations. The synthesis of trisaccharide 25 commenced with the union of glucose thioglycoside 12 with C5-linker alcohol 13 to yield the corresponding

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• intermediates, it was decided to proceed through a step-economic block synthetic strategy to achieve the target pentasaccharide derivative. Accordingly, stereoselective glycosylation of a ᴅ-galactosamine derivative 2 with a ᴅ-galactose thioglycoside derivative 3 in the presence of a combination [26][27] of N

• thioglycoside acceptor 4 in the presence of HClO4/SiO2 [31] as activator using an orthogonal glycosylation approach to furnish disaccharide thioglycoside derivative 10 in 76% yield, which was directly used in the next level of glycosylation. NMR spectral analysis of compound 10 unambiguously confirmed its

• disaccharide acceptor 9 and the disaccharide thioglycoside donor 10, a stereoselective glycosylation between them was attempted in the presence of a combination [26][27] of NIS and HClO4/SiO2 as thiophilic activator. Unfortunately, the required tetrasaccharide derivative 11 was obtained in a poor yield (22

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• can be transformed smoothly into thioglycoside [15][16][35] and sialyl halide [38][39] donors when treated with a thiol in the presence of triflic acid, BF3⋅OEt2, and HCl, respectively. Through comparison with the reported mechanism of Sc(OTf)3-catalyzed acetolysis of 1,6-anhydro-β-hexopyranoses [32

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• linker as solid support [25]. A typical AGA cycle consisted of three modules. The acidic wash module prepared the resin for glycosylation by quenching any remaining base from a previous cycle. In the glycosylation module, the thioglycoside donor was coupled to the resin upon activation with NIS and TfOH

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• ). Glycosylation of the known GlcNPhth acceptor 2 [12] and the rhamnosyl donor 3 [13] through the activation of thioglycoside using N-iodosuccinimide (NIS) in the presence of TMSOTf gave the Rha-(1→3)-GlcNPhth disaccharide 4 in 84% yield. The presence of a participating acetate group at the 2-position of the

• fluoride in THF [17] to give the 6-hydroxy compound 8 in 90% yield. It was then benzoylated using BzCl in pyridine [18] with a catalytic amount of DMAP to furnish the completely protected donor 9 in 90% yield. Glycosylation of donor 9 with disaccharide acceptor 5 through activation of the thioglycoside

• thioglycoside using NIS in the presence of TMSOTf at low temperature gave the disaccharide 16a (α) [1H NMR: 5.37 ppm (bs, 1H, H-1′), 13C NMR: 108.2 ppm (C-1′)] and 16b (β) [1H NMR: 5.36 ppm (d, J1′,2′ = 4.0 Hz, 1H, H-1′), 13C NMR: 95.6 ppm (C-1′)] in 89% yield (α:β = 2:1) (Scheme 3). Although the acceptor is

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• with high affinity to lectins and with antibiotic activities [34], lectin recognition by n-alkyl thioglycoside liposomes remains unprecedented [33][34]. Moreover, the calculated distance between the two sugar moieties of compound 8 (up to 13 Å, Figure 6) and the presence of flexible arms make these

Convergent synthesis of the pentasaccharide repeating unit of the biofilms produced by Klebsiella pneumoniae

• Arin Gucchait,
• Angana Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2019, 15, 431–436, doi:10.3762/bjoc.15.37

• unit of biofilms produced by Klebsiella pneumoniae, has been synthesized using a stereoselective [2 + 3] convergent glycosylation strategy. The β-D-mannosidic moiety has been synthesized using a D-mannose-derived thioglycoside by a two-step activation process. Late stage TEMPO-mediated oxidation of the

•  1). Initially it was planned to couple the disaccharide acceptor 13 with the trisaccharide thioglycoside donor 19 using a [3 + 2] convergent glycosylation strategy to achieve the pentasaccharide derivative 20. However, the desired product was obtained in poor yield, which did not allow upscaling of

• couple with the D-mannose-derived thioglycoside acceptor 6 in the presence of TMSOTf [35] to furnish phenyl (4,6-O-benzylidene-2,3-di-O-benzyl-β-D-mannopyranosyl)-(1→4)-(6-O-benzoyl-2,3-di-O-benzyl-α-D-glucopyranosyl)-(1→3)-4,6-O-benzylidene-2-O-benzyl-1-thio-α-D-mannopyranoside (19) in 45% yield. The

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• with simple alcohols (Scheme 20) [81][82]. In this case, of course, the sugar thioglycoside takes the role of the nucleophile rather than of the alcohol component in the Mitsunobu reaction. Reactions with NH acids to achieve N-glycosides Early on, phthalimide was regarded as a good Mitsunobu reagent

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

• construction of oligosaccharides is the combination of Lewis acids and iodine or its chemical equivalents. Fukase and co-workers reported a glycosylation reaction with thioglycoside using hypervalent iodine reagents in the 1990s [78][79]. The outline and postulated mechanism of the reaction are shown in Figure

•  7. The reaction of iodosylbenzene and electrophiles, e.g., triflic anhydride or Lewis acids, should generate a potent thiophile 143 that reacts with thioglycoside 144 to form an oxocarbenium ion 145. The resulting oxocarbenium ion 145 should in turn react with a sugar acceptor to give the

• glycosylated product 147 (Figure 7). By this reaction, Fukase et al. reported the glycosylation of methyl thioglycoside 148 as a sugar donor to give disaccharides 150 and 152 in high chemical yields as depicted in Scheme 19. As mentioned above, not only triflic anhydride, but various Lewis acids (TMSOTf, Sn

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

• was prepared following literature procedures [26]. On the other hand the D-glucosyl thioglycoside 8 was converted to the known benzylidene derivative 9 [29][30] according to our previously reported procedure. Benzylation of 9 under phase-transfer conditions led to 10 [31] in 49% yield (Scheme 1

• ). Subsequently, 10 was subjected to naphthylmethylation/p-methoxybenzylation [32] with 2-(bromomethyl)naphthalene (NapBr)/p-methoxybenzyl chloride in DMF to afford 6a/11 [32] in 90% and 80% yields, respectively. These derivatives were next subjected to thioglycoside hydrolysis using trichloroisocyanuric acid

• (TCCA) [33] in wet acetone which provided 12a/12b [34] in 85% and 89% yields, respectively. These were finally converted to their corresponding trichloroacetimidate 6b/6c [34] (Scheme 1) with yields of 93% and 90%, respectively. The L-rhamnosyl thioglycoside 14 [29][30], prepared from L-rhamnose (13

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

• ][80], including those bearing mannose-6-phosphate residues [45][46]. For example as shown in Scheme 7 sequential glycosylation of the key Manβ(1–4)GlcNAc disaccharide at positions 3 and 6, using the same selectively protected manno thioglycoside donor gave a tetrasaccharide. Removal of the silyl

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

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

• thioglycosyl building blocks as illustrated in Scheme 9 [38]. The hemiacetal donor 38 was preactivated with Ph2SO and Tf2O, and reacted with a bifunctional thioglycosyl acceptor 39 to form disaccharide 40. Interestingly, thioglycoside 40 could also be activated by Ph2SO/Tf2O. The subsequent addition of

• transformations commonly encountered in building block preparation [41]. At the same time, mild promoters are available for thioglycoside activation. The anomeric reactivities of thioglycosides towards glycosylation can be significantly influenced by the protective groups on the glycan ring as well as the size

• thioglycoside with even lower anomeric reactivity. When building blocks with suitable anomeric reactivities are selected, multiple glycosylation reactions can be carried out in one pot without the need for synthetic manipulations or purification of the advanced oligosaccharide intermediates. This strategy

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

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

• conformations and energies chose the latter linker [55]. To apply the remote glycosidation methodology to the synthesis of the 4,6-branched trisaccharide, phthaloylated thioglycoside 17 was coupled with the 6-hydroxy group of the acceptor precursor 16 in the presence of DCC and DMAP (Scheme 5). The tethering

• 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

• size of the macrocycle formed during the glycosylation (Scheme 12) [80][81]. Thioglycoside donor 45 containing a 2-O-propargyl group and acceptor 46 with an azide-containing protecting group were connected using a click reaction to afford the tethered intermediate 47. Upon treatment with NIS/TfOH

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

• thioglycosides. Results and Discussion Initially, the capability of DBDMH to activate thioglycoside 1 [32] in order to glycosylate the primary hydroxy group present in D-glucose acceptor 2 [33] was explored without any additives (Table 1, entry 1). This initial experiment furnished disaccharide 3, albeit in