Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• peptide, which can be further utilized as a Michael acceptor for a variety of nucleophiles. Based on their manganese-catalyzed allylation using Morita–Baylis–Hillman carbonates, the Ackermann group established an applicable late-stage C–H glycosylation of peptides (Scheme 12) [95]. Thus, allylative

• , a natural product scaffold, was transformed into glycosylated tryptophan 31f. It is noteworthy that this manganese(I)-catalyzed glycoconjugation method avoids racemization. Furthermore, manganese-catalyzed allylative linchpin C–H glycosylation was investigated using structurally sophisticated

• adjacent directing group (see 31h). This manganese(I)-catalyzed late-stage glycosylation provides hexaglycopeptide conjugate 31m without epimerization. Moreover, the late-stage C–H diversification process enabled bioorthogonal access to glycosylated peptides, such as a fluorescent BODIPY-labeled tryptophan

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• , State University of New York, Buffalo, NY 14260, USA 10.3762/bjoc.17.119 Abstract Glycosylation is a common posttranslational modification, and glycan biosynthesis is regulated by a set of glycogenes. The role of transcription factors (TFs) in regulating the glycogenes and related glycosylation

• relate cell-signaling pathways to TFs and cellular glycosylation state. Whereas analysis results are presented for all 29 cancer types, specific focus is placed on human luminal and basal breast cancer disease progression. Overall, the article presents a computational approach to describe TF–glycogene

• relationships, the starting point for experimental system-wide validation. Keywords: ChIP-Seq; glycoinformatics; glycosylation; TCGA transcription factor; Introduction The glycan signatures of cells and tissue are controlled by the expression pattern of 300–350 glycosylating-related genes that are together

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

• approach to provide structurally defined building blocks containing bioisosteres of ᴅ-mannuronic acid. Building on our recently reported synthesis and glycosylation capability of hydroxamate-modified ᴅ-mannuronate building blocks [11], we now demonstrate the synthesis of a second carboxylate C6-bioisostere

• for glycosylation of 3-(benzyloxycarbonylamino)-1-propanol and furnished a regioisomeric and anomeric mixture in low yield (34%, with 20% recovered starting material and 18% hydrolysed donor, 3:1, α/β). The β-linked (minor) anomer was identified through 1JC-H coupling constant data (J = 156 Hz

• ), similar to products obtained using C6-mannuronate and C6-hydroxamate donors [11]. This initial result suggests a reduced capability using C6-tetrazole donors with a primary alcohol acceptor; comparative yields for glycosylation of 3-bromopropanol using C6-hydroxamate and C6-mannuronate donors were 65–85

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

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• covalently bind Lewis basic fluoride ions in a relatively stable fluorosulfite anion (FSO2−). Herein we report the application of liquid SO2 as a promoting solvent for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, the method is applied for both

• during the glycosylation with glycosyl fluorides in liquid SO2 is proved by 19F NMR spectroscopy. A sulfur dioxide-assisted glycosylation mechanism that proceeds via solvent separated ion pairs is proposed, whereas the observed α,β-selectivity is substrate-controlled and depends on the thermodynamic

• equilibrium. Keywords: fluorosulfite; glycosyl fluoride; Lewis acid; liquid sulfur dioxide; metal-free glycosylation; Introduction The glycosylation reaction is still one of the most important and basic synthetic strategies in carbohydrate chemistry that provides access to the various types of

Simulating the enzymes of ganglioside biosynthesis with Glycologue

• Andrew G. McDonald and
• Gavin P. Davey

Beilstein J. Org. Chem. 2021, 17, 739–748, doi:10.3762/bjoc.17.64

• O-linked glycosylation, with a web-based application, O-Glycologue, that allows knockouts of enzymes of O-linked glycosylation and the assignment of custom “wild type” sets of enzyme activities to study the effects of differential knockouts on the resultant networks [15]. In this article, we

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

• Joon Min Cha,
• Dong Hyun Kim,
• Lalita Subedi,
• Zahra Khan,
• Sang Un Choi,
• Sun Yeou Kim and
• Chung Sub Kim

Beilstein J. Org. Chem. 2020, 16, 3078–3085, doi:10.3762/bjoc.16.257

• configuration at C-6 was deduced as S (the stereochemical descriptor was flipped from R to S due to an O-glycosylation at C-2, see Figure 2C, right). The 9R configuration of 1 was determined by the modified Mosher’s method [23][24][25]. The hydrolysis product of 1 (1a) was esterified with the Mosher reagents

Semiautomated glycoproteomics data analysis workflow for maximized glycopeptide identification and reliable quantification

• Steffen Lippold,
• Arnoud H. de Ru,
• Jan Nouta,
• Peter A. van Veelen,
• Magnus Palmblad,
• Manfred Wuhrer and
• Noortje de Haan

Beilstein J. Org. Chem. 2020, 16, 3038–3051, doi:10.3762/bjoc.16.253

• compared to Skyline, and GlycopeptideGraphMS. All quantification packages resulted in comparable glycosylation profiles but featured differences in terms of robustness and data quality control. Partial cysteine oxidation was identified as an unexpectedly abundant peptide modification and impaired the

• quantification. Keywords: bioinformatics; cysteine oxidation; glycoproteomics; immunoglobulins; mass spectrometry; Introduction Protein glycosylation mainly occurs in the form of N- and O-glycosylation. N-Glycans are attached to Asn within an amino acid consensus sequence (Asn-Xxx-Ser/Thr, Xxx ≠ Pro) and O

• features, such as the linkage position and anomeric configuration, make protein glycosylation a highly complex posttranslational modification (PTM). Glycoproteomics has become important for many life science disciplines, in particular for biomedical and biopharmaceutical research [3][4][5]. Glycopeptide

A consensus-based and readable extension of Linear Code for Reaction Rules (LiCoRR)

• Benjamin P. Kellman,
• Yujie Zhang,
• Emma Logomasini,
• Eric Meinhardt,
• Karla P. Godinez-Macias,
• Austin W. T. Chiang,
• James T. Sorrentino,
• Chenguang Liang,
• Bokan Bao,
• Yusen Zhou,
• Sachiko Akase,
• Isami Sogabe,
• Thukaa Kouka,
• Elizabeth A. Winzeler,
• Iain B. H. Wilson,
• Matthew P. Campbell,
• Sriram Neelamegham,
• Frederick J. Krambeck,
• Kiyoko F. Aoki-Kinoshita and
• Nathan E. Lewis

Beilstein J. Org. Chem. 2020, 16, 2645–2662, doi:10.3762/bjoc.16.215

• compliance with FAIR standards. Here, we present Linear Code for Reaction Rules (LiCoRR), version 1.0, an unambiguous representation for describing glycosylation reactions in both literature and code. Keywords: glycoinformatics; linear code; systems glycobiology; Introduction Glycans are predominantly

• development, exchange, extension, and validation of glycosylation models and analysis tools. Here we bring explicit attention to the concerns we raise above, we provide a focused, text-based representation of reaction rules that have been introduced for the purpose of formalizing these communications. GlycoCT

• , cytoplasm (bacteria and archaea), or lysosome (degradation, Man-6-P dephosphorylation and lysosomal glycoprotein biosynthesis [33][34] or paucimannose recycling [35]), are important constraints on glycosylation [36], therefore, the addition of this information to the Linear Code reaction rules provides

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases

• Julia N. Artsemyeva,
• Ekaterina A. Remeeva,
• Tatiana N. Buravskaya,
• Irina D. Konstantinova,
• Roman S. Esipov,
• Anatoly I. Miroshnikov,
• Natalia M. Litvinko and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2020, 16, 2607–2622, doi:10.3762/bjoc.16.212

• were tested in the synthesis of nelarabine, kinetin riboside, and cladribine with good to excellent yields (52–93%). Keywords: anion exchange resins; N6-benzyladenosine; cladribine; enzymatic glycosylation; kinetin riboside; nelarabine; α-ᴅ-pentofuranose-1-phosphates; phosphorolysis of nucleosides

• cited therein). The classical two-stage version of the enzymatic transglycosylation reaction [16][17][18][19][20], as well as one-pot synthesis, and the more sophisticated option employing two cross-glycosylation transformations for nucleoside synthesis [23][24][25][26][27], seemed less attractive and

• more complicated in comparison with the enzymatic reaction of a heterocyclic base with an individual PF-1Pi [17][18][27]. However, it is known that most of purine heterocycles are poorly soluble in aqueous phosphate buffers, and the use of a cross-glycosylation scheme, i.e., a purine nucleoside as a

Comparative ligand structural analytics illustrated on variably glycosylated MUC1 antigen–antibody binding

• Christopher B. Barnett,
• Tharindu Senapathi and
• Kevin J. Naidoo

Beilstein J. Org. Chem. 2020, 16, 2540–2550, doi:10.3762/bjoc.16.206

• analysis were carried out. These analyses were used to rapidly assess key features of the system, interrogate the dynamic structure of the ligand, and determine the role of glycosylation on the conformational equilibrium. The glycopeptide conformations in solution change relative to the peptide; thus a

• sequence of 20 amino acids (–His-Gly-Val-Thr-Ser-Ala-Pro-Asp-Thr-Arg-Pro-Ala-Pro-Gly-Ser-Thr-Ala-Pro-Pro-Ala–)n, and there are five sites where O-glycosylation may occur (indicated in bold). In cancerous cells, the glycans tend to be truncated or have additional sialylation [14]. For example, in mammary

• are commonly associated with cancerous cells [14]. Movahedin et al. confirmed that the glycosylation of MUC1 influences its binding to the AR20.5 murine antibody [16], specifically the Tn-antigen binds more strongly than the nonglycosylated antigen. AR20.5 is known to bind a specific epitope within

Leveraging glycomics data in glycoprotein 3D structure validation with Privateer

• Haroldas Bagdonas,
• Daniel Ungar and
• Jon Agirre

Beilstein J. Org. Chem. 2020, 16, 2523–2533, doi:10.3762/bjoc.16.204

• the validation of 3D glycoprotein structures. Keywords: electron cryomicroscopy; glycoinformatics; glycomics; Privateer; X-ray crystallography; Introduction Glycosylation-related processes are prevalent in life. The attachment of carbohydrates to macromolecules extends the capabilities of cells to

• convey significantly more information than what is available through protein synthesis and the expression of the genetic code alone. For example, glycosylation is used as a switch to modulate protein activity [1]; glycosylation plays a crucial part in folding/unfolding pathways of some proteins in cells

• [2][3]; the level of N-glycan expression regulates the adhesiveness of a cell [4]; glycosylation also plays a role in immune function [5] and cellular signalling [5][6]. At the forefront, glycosylation plays a significant role in influencing protein–protein interactions. For example, the influenza

Computational tools for drawing, building and displaying carbohydrates: a visual guide

• Kanhaya Lal,
• Rafael Bermeo and
• Serge Perez

Beilstein J. Org. Chem. 2020, 16, 2448–2468, doi:10.3762/bjoc.16.199

• hand, the Glycan Modeler allows in silico N-/O-glycosylation for glycan-protein complexes and generates a “most relevant” glycan structure through Glycan Fragment Database (GFDB) [68] search which gives proper orientations relative to the target protein. In the absence of target glycan sequence in GFDB

• . Subsequently, a glycosylation model can be prepared for carbohydrate polymer simulation using the prepreader.py script. Similarly, the doglycans.py script can be used to develop models for glycoproteins and glycolipids. Together, these tools are called doGlycans toolset. Although doGlycans is highly flexible

• utilities for virtual glycosylation, protein–glyco-ligand docking, and glycan “loop” modelling. This tool is best for the researcher with basic knowledge and skills to work with a command-line interface (Linux). PolysGlycanBuilder. PolysGlycanBuilder [76] is a web-based tool (http://glycan

GlypNirO: An automated workflow for quantitative N- and O-linked glycoproteomic data analysis

• Toan K. Phung,
• Cassandra L. Pegg and
• Benjamin L. Schulz

Beilstein J. Org. Chem. 2020, 16, 2127–2135, doi:10.3762/bjoc.16.180

• Queensland, St. Lucia, QLD 4072, Australia 10.3762/bjoc.16.180 Abstract Mass spectrometry glycoproteomics is rapidly maturing, allowing unprecedented insights into the diversity and functions of protein glycosylation. However, quantitative glycoproteomics remains challenging. We developed GlypNirO, an

• statistical workflows. We used GlypNirO to analyse a published plasma glycoproteome dataset and identified changes in site-specific N- and O-glycosylation occupancy and structure associated with hepatocellular carcinoma as putative biomarkers of disease. Keywords: glycoproteomics; mass spectrometry; N

• -glycosylation; O-glycosylation; Python; Introduction Glycosylation is a key post-translational modification critical for protein folding and function in eukaryotes [1][2][3]. Diverse types of glycosylation are known, all involving modification of specific amino acid residues with complex carbohydrate

Clustering and curation of electropherograms: an efficient method for analyzing large cohorts of capillary electrophoresis glycomic profiles for bioprocessing operations

• Ian Walsh,
• Matthew S. F. Choo,
• Sim Lyn Chiin,
• Amelia Mak,
• Shi Jie Tay,
• Pauline M. Rudd,
• Yang Yuansheng,
• Andre Choo,
• Ho Ying Swan and
• Terry Nguyen-Khuong

Beilstein J. Org. Chem. 2020, 16, 2087–2099, doi:10.3762/bjoc.16.176

• , Faculty of Engineering, National University of Singapore (NUS), Singapore 117575 10.3762/bjoc.16.176 Abstract The accurate assessment of antibody glycosylation during bioprocessing requires the high-throughput generation of large amounts of glycomics data. This allows bioprocess engineers to identify

• critical process parameters that control the glycosylation critical quality attributes. The advances made in protocols for capillary electrophoresis-laser-induced fluorescence (CE-LIF) measurements of antibody N-glycans have increased the potential for generating large datasets of N-glycosylation values

• ; electropherogram; glycosylation; monoclonal antibodies; peak picking; process development; Introduction Glycosylation is important for the efficacy and function of a majority of the most dominant biologic drugs currently on the global market. In the case of antibody-based biotherapeutics, the absence of

How and why plants and human N-glycans are different: Insight from molecular dynamics into the “glycoblocks” architecture of complex carbohydrates

• Carl A. Fogarty,
• Aoife M. Harbison,
• Amy R. Dugdale and
• Elisa Fadda

Beilstein J. Org. Chem. 2020, 16, 2046–2056, doi:10.3762/bjoc.16.171

• Carl A. Fogarty Aoife M. Harbison Amy R. Dugdale Elisa Fadda Department of Chemistry and Hamilton Institute, Maynooth University, Maynooth, Kildare, Ireland 10.3762/bjoc.16.171 Abstract The N-glycosylation is one of the most abundant and diverse post-translational modifications of proteins

• flexible and highly dynamic at room temperature, thus their characterization through experimental structural biology methods is hardly straightforward even in cryogenic environments [6]. As an additive layer of difficulty, glycosylation is only indirectly dependent on the genome, which often results in a

• ][21][22][23]. More specifically, we investigate how core α(1-3)-linked fucose (Fuc) and β(1-2)-linked xylose (Xyl) affect the structure and dynamics of plants N-glycoforms [23] and of hybrid constructs with mammalian N-glycoforms [24]. At first glance plants protein N-glycosylation [23] is quite

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• catalytic hydrogenolysis over Pd/C under 15 kg/cm2 of H2 to give the target lipid X monosaccharide 1 (as triethylammonium salt) in good yield. Having the glycosyl donor 20 and acceptor 18 at hand (Scheme 2), in order to prepare the disaccharide precursor, the glycosylation reaction was performed first

• , followed by deprotection, acylation, and phosphorylation reactions (Scheme 4). The triflic acid (TfOH)-mediated glycosylation of donor 20 and acceptor 18 in the presence of molecular sieves in CH2Cl2 at −20 °C gave disaccharide 24 [14] in excellent yield (β-anomer only). The N’-Troc protecting group (non

• , acylation, phosphorylation, and global deprotection. The glycosyl acceptor and donor for the synthesis of the disaccharide precursor could also be readily obtained starting from the same key building block. After glycosylation, the disaccharide lipid A precursor 2 was synthesized following a similar

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• glycosylation is described. Two short-chain glycolipid analogs that mimic the naturally occurring substrate mannosyl phosphoryl dolichol exhibit either photoreactive and clickable properties or allow the use of a fluorescence readout. Both probes consist of a hydrophilic mannose headgroup that is linked to a

• glycolipid analogs; scramblase; Introduction Mannosyl phosphoryl dolichol (MPD), an important, multifunctional glycolipid, is used as a mannose donor for protein N-glycosylation, O- and C-mannosylation, and glycosylphosphatidylinositol (GPI) anchoring in the luminal leaflet of the endoplasmic reticulum (ER

• Financial support by the Swiss National Science Foundation (SNSF) is gratefully acknowledged: This research was funded by the Sinergia Project: Molecular identification of lipid transporters for protein glycosylation, Grant CRSII5_170923.

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

• the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71T in a very good yield adopting sequential glycosylation followed by removal of the p-methoxybenzyl (PMB) group in the same pot. Further, the synthetic strategy was modified by carrying out three stereoselective iterative

• glycosyl activator. Keywords: Azospirillum doebereinerae; glycosylation; HClO4-SiO2; O-polysaccharide; tetrasaccharide; Introduction The development of plant-growth-promoting agents has become an attractive area of research in the agricultural sciences to reduce the need for chemical fertilizers, which

• glycosylation in one pot was developed and is reported herein. Results and Discussion At the beginning, the retrosynthetic analysis suggested that a sequential glycosylation reaction using judiciously protected monosaccharide thioglycosides could be the best strategy for achieving the desired tetrasaccharide 1

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

• -mannosidic linkage, have to be installed stereoselectively while taking provision to install the C-6 O-acetate in ManpNAc. The synthetic approach (Scheme 1) relies on a late stage [2 + 3] α-glycosylation between disaccharide 6 and trisaccharide 7 to obtain the fully protected pentasaccharide RU. The di- and

• the β-disaccharide 16 (Scheme 2). A ring-opening reaction followed by subsequent glycosylation of 19 with orthogonally protected thioglucoside 10 gave trisaccharide 21 in moderate yield. To improve the yield, the nucleophilicity of the disaccharide acceptor 19 (Scheme 2) was altered by replacing the

• benzoate esters in 16 by a benzyl ether leading to compound 17. The latter then was converted into the more reactive acceptor 20 via a ring-opening reaction. Glycosylation of 20 with thioglucoside 10 resulted in the desired trisaccharide 22 in almost twice the yield when compared to trisaccharide 21

Synthesis of new asparagine-based glycopeptides for future scanning tunneling microscopy investigations

• Laura Sršan and
• Thomas Ziegler

Beilstein J. Org. Chem. 2020, 16, 888–894, doi:10.3762/bjoc.16.80

• pathogenesis [1][2][3][4]. Glycosylation is also considered to be one of the most important post-translational modification (PTM) since more than half of all human proteins are glycopeptides or glycoproteins [5]. Therefore, understanding how glycopeptides interact on an intra- and intermolecular level is

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

• protic acid glycosyl activator. The expected configuration at the glycosidic linkages was achieved using a reasonable selection of protecting groups in the manosaccharide intermediates. Keywords: Escherichia albertii O4; glycosylation; HClO4/SiO2; O-antigen; pentasaccharide; Introduction Diarrheal

• fragments with adequate purity. In this direction, the total synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigenic polysaccharide of the E. albertii O4 strain using a sequential glycosylation strategy is presented herein (Figure 1). Results and Discussion The synthesis

• 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

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

• distinguished these alcohols by selective protection of the OH-7 functionality as 2,7-anhydro-Neu5Ac, leaving position OH-4 free for glycosylation upon protection of the vicinal OH-8 and OH-9 substituents as benzylidene or acetonide rings [6]. The formation of the bicyclo[3.2.1] backbone of 2,7-anhydro-Neu5Ac

• compound 12. Due to the absence of a hydrogen bond, azido-protected glycal 13 could be used as acceptor for reactions at its OH-4 and OH-8 group [36][37]. Moreover, it was used as sialyl donor in α-selective glycosylation reactions [35]. Next, acetolysis of 2,7-anhydro derivative 6 was examined with SnCl4

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

• analyzed the relative reactivity of the OH-3 and OH-4 groups of 2,6-diprotected methyl α- and β-galactopyranoside derivatives in glycosylation reactions. The glycosyl acceptors were efficiently prepared by simple methodologies, and glycosyl donors with different reactivities were assessed. High

• effort [1]. Therefore, a carefully designed plan is necessary before starting the synthesis of the desired target structure. Such a plan must include the choice of the glycosylation strategy for the formation of each glycosidic bond, as well as the design of derivatives with temporary protecting groups

• 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

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

• after each glycosylation and further optimized reaction conditions allowed for the synthesis of a series of oligosaccharides, ranging from hexa- to branched dodecasaccharides. Keywords: arabinomannan; automated glycan assembly; capping; Introduction Bacterial infections caused by MTB killed 1.7

• 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

• glycosylation cycles using 6.5 equiv of BB 1 afforded compound 5 in 37% yield. Chromatographic analysis revealed compound 5 as the major product, along with pentamer and tetramer side products from incomplete glycosylation. To improve the glycosylation efficiency, a new glycosylation module employing higher