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

• allowed efficient access to the trisaccharide target via stepwise glycosylation as well as a one-pot glycosylation protocol. In a different approach, a 4,6-O-benzylidene D-manno-trisaccharide derivative was synthesized, which upon global 6-O-deoxygenation followed by deprotection generated the target D

• -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

• , further optimization of the glycosylation protocol was achieved by carrying out the whole glycosylation process in one-pot leading to the target trisaccharide 9 in 79% yield (Scheme 3). In this case the disaccharide synthesis was set up as described previously, and then the second acceptor 7 was

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• pharmacokinetic properties of a protein, N-PEGylation may be used additively to N-glycosylation since both modifications stabilize the protein by different mechanisms [25]. Also, glutamine residues on intact or chimeric proteins can be combined with alkylamino-PEG derivatives by the use of a transglutaminase [26

• is transferred to the glycan by a sialyltransferase. The serine or threonine residues in the O-glycosylation sites serve as acceptors for GalNAc using a convenient GalNAc transferase. This unit can be galactosylated by a galactosyltransferase and both, the monosaccharide and the disaccharide, may be

• chitosan derivative, adapted from [61]. Chitosan/PEG functionalized with a mannose at the distal end, adapted from [62]. Chemoenzymatic method for the preparation of PEG-CMP-SA, adapted from [32][33]. GlycoPEGylation by sequential in vitro, enzyme mediated, O-glycosylation followed by transfer of PEGylated

Design and synthesis of multivalent neoglycoconjugates by click conjugations

• Feiqing Ding,
• Li Ji,
• Ronny William,
• Hua Chai and
• Xue-Wei Liu

Beilstein J. Org. Chem. 2014, 10, 1325–1332, doi:10.3762/bjoc.10.134

• hydroamination/glycosylation on glycal scaffolds has been developed to form propargyl 3-tosylamino-2,3-dideoxysugars in a one-pot manner. Subsequent construction of multivalent 3-tosylamino-2,3-dideoxyneoglycoconjugates with potential biochemical applications was presented herein involving click conjugations as

• /glycosylation of the glycal shown in Figure 1 [49][50][51][52][53]. Extending the synthetic utility of this protocol, herein, we wish to report the synthetic modification of α-GalNAc-linked glycopeptides to 3-tosylamino-2,3-dideoxyneoglycoconjugates via click conjugations (Figure 2). Given the success in using

• “click chemistry” in the glycosylation reactions, we aspired to apply the highly efficient triazole formation employing an azide 3 and a suitable alkyne appended to the 3-amino-2,3-dideoxysugars moiety 2 (Figure 3). In continuation of our previous work, herein we report a direct and reliable synthetic

Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16-sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation

• Hannes Mikula,
• Julia Weber,
• Dennis Svatunek,
• Philipp Skrinjar,
• Gerhard Adam,
• Rudolf Krska,
• Christian Hametner and
• Johannes Fröhlich

Beilstein J. Org. Chem. 2014, 10, 1129–1134, doi:10.3762/bjoc.10.112

• natural product conjugates. Keywords: glycosylation; masked mycotoxins; resorcylic acid esters; sulfation; zearalenone; Introduction Resorcylic acid lactones (RALs, Figure 1), a compound class of benzannulated macrolides, are pharmacologically active secondary metabolites produced by a variety of

• glycosylation has been reported by Grabley et al. [14]. ZEN-14-sulfate (6, Figure 2A) was first isolated from F. graminearum-inoculated rice [15] and both, the glucoside 5 and the sulfate 6, were identified as ZEN metabolites in Arabidopsis thaliana [16]. These conjugates are easily hydrolyzed back to the

• -glucoside than ZEN-14-glucoside in barley roots [17]. We therefore intended to develop a synthetic method for regiocontrolled conjugation of ZEN. Basically, the RAL type moiety of ZEN contains two possible sites for glycosylation/sulfation, but due to the higher reactivity of the phenol group at position 14

Efficient carbon-Ferrier rearrangement on glycals mediated by ceric ammonium nitrate: Application to the synthesis of 2-deoxy-2-amino-C-glycoside

• Alafia A. Ansari,
• Y. Suman Reddy and
• Yashwant D. Vankar

Beilstein J. Org. Chem. 2014, 10, 300–306, doi:10.3762/bjoc.10.27

• glycosyl amino acids [52] to name but a few. Amongst the various reported methods to prepare these compounds [53][54][55], the most common method is via C-glycosylation of 2-aminosugars [56][57][58], which is challenging owing to the incompatibility of protic or Lewis acids with amino and amido

Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

• Pintu Kumar Mandal,
• Debashis Dhara and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2014, 10, 293–299, doi:10.3762/bjoc.10.26

• protected monosaccharide intermediates in 42% overall yield in seven steps by using a [2 + 2] block glycosylation approach. Keywords: Azospirillum brasilense; glycosylation; lipopolysaccharide; plant growth-promoting bacteria (PGPB); tetrasaccharide; Introduction The intensive use of chemicals for the

• (e.g. a protein, a lipid or another aglycone) for biochemical applications. A stereoselective [2 + 2] block glycosylation of the disaccharide derivative 8 with the disaccharide thioglycoside 9 led to the formation of tetrasaccharide 10, which was finally deprotected to give the desired tetrasaccharide

• 1. A number of suitably functionalized monosaccharide intermediates 2, 3 [30], 4 [31], and 5 [32] were prepared from the reducing sugars by using literature reports. The application of a one-pot reaction sequence for the stereoselective glycosylation and the removal of the p-methoxybenzyl (PMB

The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030

• Tobias A. M. Gulder,
• Snežana Neff,
• Traugott Schüz,
• Tammo Winkler,
• René Gees and
• Bettina Böhlendorf

Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293

• O-methylation, glycosylation, prenylation, oxygenation and subsequent cyclization or dimerization events [34]. Nitrogen-bearing congeners are rather scarce, with the bacterial aminocoumarins, such as the gyrase inhibitor novobiocin, being the most well-known examples [35]. Despite the larger number

Synthesis of homo- and heteromultivalent carbohydrate-functionalized oligo(amidoamines) using novel glyco-building blocks

• Felix Wojcik,
• Sinaida Lel,
• Alexander G. O’Brien,
• Peter H. Seeberger and
• Laura Hartmann

Beilstein J. Org. Chem. 2013, 9, 2395–2403, doi:10.3762/bjoc.9.276

• heteromultivalent glycosylation patterns by combining building blocks presenting different mono- and disaccharides. Keywords: continuous flow; flow chemistry: flow synthesis; glycoligands; multivalency; photochemistry; solid-phase synthesis; thiol–ene; thioglycosides; Introduction Multivalent carbohydrate ligand

• resulting in three monodisperse, sequence-defined glycooligomers with different glycosylation patterns. The building-block approach for the synthesis of glycooligomers thus allows for the control of the ligand positioning as well as the straightforward introduction of defined sequences of different types of

Gold-catalyzed glycosidation for the synthesis of trisaccharides by applying the armed–disarmed strategy

• Abhijeet K. Kayastha and
• Srinivas Hotha

Beilstein J. Org. Chem. 2013, 9, 2147–2155, doi:10.3762/bjoc.9.252

• two steps. The glycosylation between disaccharide 24 and disarmed aglycon 16 was performed under aforementioned conditions for a gold-catalyzed transglycosidation. Purification by conventional silica gel column chromatography enabled us to characterize the anticipated trisaccharide 25 (21%) along with

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• of the putative tetracenomycin-like intermediate 210, the aldehyde 211 is reduced to the corresponding alcohol 212. Acetalization and introduction of the 1,2-cis-diol moiety furnishes 213. Sequential formation of the lactone and the isoindolinone generates 214. A final glycosylation step leads to

• diastereoselective synthesis of lactonamycinone (214) employing a Diels–Alder reaction [162][163]. In 2010, Tastuta completed the first total synthesis of lactonamycin (215) by using a sequential conjugate addition, a stereoselective glycosylation reaction and a Michael–Dieckmann-type cyclization [164]. The recently

• published total synthesis of lactonamycin (215) and lactonamycin Z (217) by Saikawa and Nakata is based on a late-stage glycosylation strategy (Scheme 29). This enables the specific variation of the sugar components and gives access to various lactonamycin derivatives [161]. Starting from alcohol 219, the

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

• help us understand the biological and disease implications of these glycosylation patterns at both molecular and functional levels. However, despite the need for functional studies of O-glycosylation patterns, there are comparatively few reported syntheses leading to the basic mucin-type cores [9][10

• versatile blockwise strategy was employed to prepare targets 2–4, whereby each glycosylation product yielded compounds that were either deprotected to give the final products or became the acceptor for the next glycosylation step. The synthesis started from orthogonally protected 3-chloropropyl-α-linked

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• achieved following a sequential glycosylation strategy. A minimum number of steps was used for the synthesis of the target compound involving a one-pot glycosylation and a protecting group manipulation. All intermediate reactions afford their products in high yield, and the glycosylation steps are

• stereoselective. Keywords: Escherichia coli; glycosylation; lipopolysaccharide; O-antigen; tetrasaccharide; Introduction Neonatal meningitis is a serious concern in developing countries [1]. The symptoms associated with this disease are unspecific and may ultimately lead to sepsis [2]. The common cause of the

• presented herein (Figure 2). Results and Discussion The target tetrasaccharide as its p-methoxyphenyl (PMP) glycoside was synthesized following a sequential glycosylation approach from the suitably functionalized monosaccharide intermediates 2 [13], 3 [14], 4 [15] and 5 [16]. These monosaccharide

Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols

• Tamashree Ghosh,
• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 974–982, doi:10.3762/bjoc.9.112

• carbonotrithioate. The reaction conditions are reasonably simple and yields were very good. Keywords: Appel reagent; carbon tetrabromide; glycosyl hemiacetal; glycosyl thiol; thioglycoside; triphenylphosphine; Introduction Thioglycosides (1-thiosugar) are widely used glycosyl donors in glycosylation reactions [1

Short synthesis of the common trisaccharide core of kankanose and kankanoside isolated from Cistanche tubulosa

• Goutam Guchhait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 705–709, doi:10.3762/bjoc.9.80

• isolated from the medicinally active plant Cistanche tubulosa. All glycosylations were carried out under nonmetallic reaction conditions. Yields were very good in all intermediate steps. Keywords: Cistanche tubulosa; glycosylation; kankanoside; synthesis; trisaccharide; Introduction Cistanche tubulosa (C

• , H2 and I isolated from C. tubulosa thereby exploiting newly developed regio- and stereoselective glycosylation conditions (Figure 1). This straightforward synthetic strategy employs a minimum number of steps. Results and Discussion The target trisaccharide 1 in the form of its 2-phenylethyl glycoside

• presence of molecular iodine [13] furnished compound 5 in 86% yield. Regioselective 3-O-glycosylation of compound 5 with L-rhamnose derived trichloroacetimidate derivative 3 [11] in the presence of NOBF4 [14] followed by acetylation in the same pot furnished disaccharide derivative 6 in 76% yield. In this

De novo synthesis of D- and L-fucosamine containing disaccharides

• Daniele Leonori and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 332–341, doi:10.3762/bjoc.9.38

• influenced by their glycosylation patterns [1][2]. Therefore, an understanding of protein glycosylation is of utmost importance in order to develop new therapeutics [3][4][5][6]. The ability of bacteria to colonize human hosts and cause diseases is directly influenced by their capacity to synthesize

• microarray platform and their conjugation to carrier proteins, an appropriate linker was required at the anomeric position [67]. Placement of a C3 naphthyl ether anticipated the site for further glycosylation at this position, which typically serves as the connection to the next sugar. Therefore, building

• block 8a is ideal in terms of orthogonality and chemical synthesis. Hence, we tested the ability of D-8a to undergo anomeric functionalization and to effect glycosylation at the C3 hydroxy group. Due to the presence of N-acetylated D- and L-fucosamine residues in P. aeruginosa O-linked glycans, the

Synthesis and testing of the first azobenzene mannobioside as photoswitchable ligand for the bacterial lectin FimH

• Vijayanand Chandrasekaran,
• Katharina Kolbe,
• Femke Beiroth and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2013, 9, 223–233, doi:10.3762/bjoc.9.26

• , glycosylation of the key intermediate 10 by using the mannosyl donor 3 gave the desired mannobioside 11 in 76% yield. Finally, removal of the O-acetyl groups according to Zemplén led to the unprotected 1,3-linked target mannobioside α-D-Man-(1→3)-D-Man (2). With the two azobenzene glycosides 6 and 2 at hand

• , open-gate conformation). Bottom: (Z)-isomer (C, closed-gate; D, open-gate conformation). Synthesis of azobenzene mannoside 6 and azobenzene mannobioside 2 by glycosylation. Characterisation of the (E)- and (Z)-isomers of azobenzene glycosides 6 and 2. Inhibition of adhesion of E. coli to a mannan

Efficient synthesis of phenylene-ethynylene rods and their use as rigid spacers in divalent inhibitors

• Francesca Pertici,
• Norbert Varga,
• Arnoud van Duijn,
• Matias Rey-Carrizo,
• Anna Bernardi and
• Roland J. Pieters

Beilstein J. Org. Chem. 2013, 9, 215–222, doi:10.3762/bjoc.9.25

• rigid linkages between functional units. Examples of these have been reported in areas such as nanoelectronics and nanooptics [1], surfactants [2][3][4], photoelectrochemical detection [5], catalysis [6], glycosylation reactions [7], and carbohydrate–protein interactions [8]. Many different strategies

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

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

• /bjoc.9.13 Abstract Automated oligosaccharide assembly requires suitable linkers to connect the first monosaccharide to a solid support. A new hydrogenolysis-labile linker that is stable under both acidic and basic conditions was designed, synthesized and coupled to different resins. Glycosylation and

• 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

Peptoids and polyamines going sweet: Modular synthesis of glycosylated peptoids and polyamines using click chemistry

• Daniel Fürniss,
• Timo Mack,
• Frank Hahn,
• Sidonie B. L. Vollrath,
• Katarzyna Koroniak,
• Ute Schepers and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 56–63, doi:10.3762/bjoc.9.7

• fast methods for the decoration of biomimetic molecules with sugars is of fundamental importance. The glycosylation of peptoids and polyamines as examples of such biomimetic molecules is reported here. The method uses Cu-catalyzed azide alkyne cycloaddition to promote the reaction of azidosugars with

• copper ions. In some cases, changing the base from DIPEA to DBU was beneficial (Scheme 2). After these encouraging results, we turned our attention to peptoids. For the glycosylation of peptoids, we envisaged the generation of a fully glycosylated peptoid in order to investigate the compatibility of

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• synthesis of α-D-Galf-(1→2)-D-galactose by the same glycosylaldonolactone approach [25]. The same derivative 4 was envisaged as precursor of 1 due to the high regioselectivity previously achieved in glycosylation at HO-2. Additionally, this procedure would afford derivative 8, a valuable intermediate for

• in Et2O, employing TMSOTf as catalyst, proceeded with complete regio- and stereoselectivity, affording the α-glycosylaldonolactone 5 in 79% yield (Scheme 1). The α-anomeric configuration and the regioselectivity of the glycosylation were confirmed on the basis of the NMR spectra. In the 1H NMR

• into an apparent triplet. On the other hand, in the 13C NMR spectrum of 5 the signal corresponding to C-1 appeared at δ 170.1, shifted 4 ppm in comparison with the corresponding signal of 4, as result of glycosylation at the vicinal position [28]. For the reduction of the lactone function, compound 5

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

• 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

• . In the process of evaluating the performance of this linker in solid-phase glycosylation reactions, the potential as well as some severe limitations became apparent. Linker 10 is the newly designed acylsulfonamide safety-catch linker (Scheme 1). The safety-catch linkage to the resin permits

• acylsulfonamide safety-catch linker 10 plus the Zemplén cleavage site, were employed in glycosylation reactions on a solid phase using an automated synthesizer [13], subsequently cleaved with NaOMe, and the products were analyzed by HPLC (Scheme 3, see Supporting Information File 1). Glycosylations were performed

Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of Escherichia coli O40

• Abhijit Sau and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2012, 8, 2053–2059, doi:10.3762/bjoc.8.230

• using a convergent block glycosylation strategy. A disaccharide donor was coupled to a disaccharide acceptor by a stereoselective glycosylation. A 2-aminoethyl linker was chosen as the anomeric protecting group at the reducing end of the tetrasaccharide. All glycosylation steps are significantly high

• yielding and stereoselective. Keywords: Escherichia coli; glycosylation; lipopolysaccharide; O-antigen; tetrasaccharide; Introduction Infantile diarrhoea is one of the major causes of morbidity and mortality in infancy in developing countries [1]. Among several factors, Escherichia coli (E. coli

• strategy. Results and Discussion The target tetrasaccharide 1 as its 2-aminoethyl glycoside was synthesized by a stereoselective glycosylation of a disaccharide acceptor 8 and a disaccharide thioglycoside donor 9 using a [2 + 2] block synthetic strategy. The disaccharide intermediates were synthesized from

Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• polyproline helix type II (PPII) [13]. The larger AFGP1-4 are known to form flexible rods with segmental mobility [14][15]. Recent research has been directed toward the assembly of synthetic AFGPs with tailored amino acid composition and glycosylation pattern. The main target is to investigate the influence

• recrystallization assays. The glycosylation of threonine in D- and allo-L-configuration with N-acetyl galactosamine relies on an efficient synthetic procedure by Paulsen et al. [21] adapted by us [16][22][23] (Scheme 1). Azidochlorination of a suitably protected L-galactal provides the peracetylated 2-azido-2

• -desoxygalactopyranosyl chloride serving as a glycosyl donor in a silver-mediated Koenigs–Knorr glycosylation of the particular Fmoc- and t-Bu-protected amino acids, i.e., the allo-L-configured (1A) and D-configured (1B) threonine derivatives. Both glycosylated amino acids (2) were obtained in good yields and very good

The Amadori rearrangement as glycoconjugation method: Synthesis of non-natural C-glycosyl type glycoconjugates

• Katharina Gallas,
• Gerit Pototschnig,
• Florian Adanitsch,
• Arnold E. Stütz and
• Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2012, 8, 1619–1629, doi:10.3762/bjoc.8.185

• chemistry (Huisgen cycloaddition) [4][5], glycosylation protocols [6][7], and Staudinger ligation [8], just to mention the most prominent examples. However, many applications in this respect require a ligation method that is functional in aqueous medium, and, for economic purposes in general, protecting