Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• described by Patil and Kartha [89], where the preparation of thioglycosides was almost quantitative. Unfortunately, a lack of information on reaction mixture compositions means that the reaction mechanism cannot be completely confirmed because chromatographic purifications and recrystallizations distort the

Synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4

• Pintu Kumar Mandal

Beilstein J. Org. Chem. 2014, 10, 2724–2728, doi:10.3762/bjoc.10.287

• been synthesized using a combination of sequential glycosylations and [3 + 2] block synthetic strategy from the suitably protected monosaccharide intermediates. Thioglycosides and glycosyl trichloroacetimidate derivatives have been used as glycosyl donors in the glycosylations. Keywords: Escherichia

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

• the A-band polysaccharide of Pseudomonas aeruginosa. One of the key steps involved 6-O-deoxygenation of either partially or fully acylated 4,6-O-benzylidene-1-thiomannopyranoside by radical-mediated redox rearrangement in high yields and regioselectivity. The D-rhamno-thioglycosides so obtained

• thioglycosides directly. Moreover, the use of stoichiometric amounts of the toxic tin hydride for radical-based reductive dehalogenation as required by the above method appeared undesirable especially in the preparative stages where reactions have to be set up on a large scale. On the other hand, Kiefel’s method

• . [28] and subsequently studied by Dang et al. [29][30][31][32] which seemed to address all the inadequacies described above. However, the compatibility of the method with thioglycosides had to be verified. Upon application, and much to our delight, it was found that thioglycosides responded equally

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

• summary, a straightforward and convergent synthesis of the tetrasaccharide 1 as its 2-aminoethyl glycoside corresponding to the O-specific polysaccharide of the LPS of A. brasilense strain Sp7 has been presented. The use of thioglycosides both as glycosyl donor and acceptor according to the concept of the

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

• thioglycosides to a double-bond presenting diethylentriamine precursor is the key step to prepare these building blocks suitable for fully automated solid-phase synthesis. Introduction of the sugar ligands via functionalized building blocks rather than postfunctionalization of the oligomeric backbone allows for

• 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

• photoreactor was developed involving post functionalization of alkene presenting oligomers by thioglycosides [26]. The flow system allows for precise control over the reaction conditions, is easy to scale up and provides efficient irradiation of the samples by virtue of a sub-millimeter path length. Continuous

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

• and acceptors that both have a free hydroxy group [27]. In this report, we employed the difference in reactivity of trichloroacetimidates and thioglycoside donors. In general, trichloroacetimidates are activated by strong Lewis acids such as TMSOTf [28], while the more stable thioglycosides require

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

• intermediates were prepared from the commercially available reducing sugars by using a number of recently developed reaction conditions (Figure 2). The notable features of the synthetic strategy include, (a) the use of thioglycosides as glycosyl donors in all glycosylation reactions; (b) the application of

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

• Tamashree Ghosh Abhishek Santra Anup Kumar Misra Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII-M, Kolkata-700054, India, Fax: 91-33-2355 3886 10.3762/bjoc.9.112 Abstract A series of glycosyl hemiacetal derivatives have been transformed into thioglycosides and glycosyl

• thiols in a one-pot two-step reaction sequence mediated by Appel reagent (carbon tetrabromide and triphenylphosphine). 1,2-trans-Thioglycosides and β-glycosyl thiol derivatives were stereoselectively formed by the reaction of the in situ generated glycosyl bromides with thiols and sodium

• 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

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

• activated by TMSOTf were conducted, and followed by Zemplén cleavage. Similarly, three equivalents of thioglycosides 17 and 19 were added three times (triple coupling) for each glycosylation employing DMTST or NIS/TfOH as an activator. In both instances, surprisingly, only N-glycoside 20 (minor product) and

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

• , which include (a) stereoselective [2 + 2] block glycosylation; (b) application of general glycosylation reactions by using thioglycosides as glycosyl donors and a combination of N-iodosuccinimide (NIS) and perchloric acid supported over silica (HClO4–SiO2) [17][18] as glycosyl activator; (c

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

• automated synthesis of α-(2→6) sialosides (Scheme 6). The synthesis of tetrasaccharide 30 started with the glycosylation of linker 17 by using galactose building block 28 under standard conditions for the activation of thioglycosides, followed by Fmoc removal and a glycosylation with building block 18. The

2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis

• Hemali D. Premathilake and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2012, 8, 597–605, doi:10.3762/bjoc.8.66

• activated for chemical glycosylation under a variety of conditions, through both direct and remote pathways. Differentiation between the two activation pathways was achieved in a mechanistic study. The orthogonal-type activation of the AP moiety along with common thioglycosides allows for the execution of

• orthogonality was shown for O-pentenyl versus O-propargyl glycosides by Hotha et al. [17] and for S-glycosyl O-methyl phenylcarbamothioate (SNea) versus thioglycosides/thioimidates by us [18], but still their applicability to multistep synthesis remains to be proven. Working to expand this concept, our group

• category of leaving groups, because they can be glycosidated under mild conditions by using I+ generated in situ. Also this method has its limitations since I+ can also activate thioglycosides. Indeed, only the semiorthogonality of the O-pentenyl and SEt leaving groups could be established [19

Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation

• Toshiki Nokami,
• Akito Shibuya,
• Yoshihiro Saigusa,
• Shino Manabe,
• Yukishige Ito and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2012, 8, 456–460, doi:10.3762/bjoc.8.52

• , Wako, Saitama 351-0198, Japan 10.3762/bjoc.8.52 Abstract Glycosyl triflates with a 2,3-oxazolidinone protecting group were generated from thioglycosides by low-temperature electrochemical oxidation. The glycosyl triflates reacted with alcohols to give the corresponding glycosides β-selectively at low

• , play an important role in the stereoselective formation of both α- and β-isomers. We have developed an electrochemical method to generate and accumulate highly reactive glycosyl triflates by low-temperature electrochemical oxidation of thioglycosides [26][27][28][29][30]. Although Kerns and Ye have

• -trans linkages in the presence of a base at low temperatures and 1,2-cis glycosidic linkages in the absence of a base at elevated temperatures. Results and Discussion We began by conducting the electrochemical oxidation of 2,3-oxazolidinone thioglycosides 1a–1c in the absence of a glycosyl acceptor at

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

• Patrick Claude,
• Christian Lehmann and
• Thomas Ziegler

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

• thioglycosides under activation with NIS. Best results were obtained with a 1:1 mixture of CH2Cl2 and MeCN. All intramolecular couplings proceeded smoothly at −5 °C within one hour. The products 6−8 were purified by conventional chromatography on silica gel with mixtures of CH2Cl2 and acetone as the eluent. For

Synthesis of 6-PEtN-α-D-GalpNAc-(1–>6)-β-D-Galp-(1–>4)-β-D-GlcpNAc-(1–>3)-β-D-Galp-(1–>4)-β-D-Glcp, a Haemophilus influenzae lipopolysacharide structure, and biotin and protein conjugates thereof

• Andreas Sundgren,
• Martina Lahmann and
• Stefan Oscarson

Beilstein J. Org. Chem. 2010, 6, 704–708, doi:10.3762/bjoc.6.80

• the title compound have been constructed to allow further use in biological experiments. Keywords: conjugate vaccines; glycoconjugates; Haemophilus influenzae; lacto-N-neotetraose; oligosaccharide synthesis; thioglycosides; Introduction Haemophilus influenzae are Gram-negative bacteria divided into

Benzyne arylation of oxathiane glycosyl donors

• Martin A. Fascione and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2010, 6, No. 19, doi:10.3762/bjoc.6.19

• turn the α-directing participating group into an anomeric leaving group reactive enough to partake in glycosylations. Thioglycosides are widely used as glycosyl donors [14][15], and many different reagents are available for their activaton including N-iodosuccinimide (NIS)/TMSOTf [16], dimethyl

• endeavours to achieve this goal and the first use of benzyne as an activating agent for thioglycosides [24]. Results and Discussion The method chosen for in situ benzyne (9) generation was the reaction of 1-aminobenzotriazole (1-ABT) (8) with lead tetraacetate by the procedure pioneered by Rees and co

Study of thioglycosylation in ionic liquids

• Jianguo Zhang and
• Arthur Ragauskas

Beilstein J. Org. Chem. 2006, 2, No. 12, doi:10.1186/1860-5397-2-12

• reported to promote the formation of a glycoside bond which include, classical glycosyl halides, thioglycosides, pentenyl glycosides, anomeric trichloroacetimidates and others.[13] As reviewed by Oscarson,[14] thioalkyl or thioaryl glycosyl donors have been shown to exhibit excellent selectivity and