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

• synthesis of the O-antigens, that of Providencia rustigianii O34 was reported by Mukhopadhyay et al. in 2013 [34]. Chheda and co-worker, in 2015, reported the total synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide of Providencia alcalifaciens O28 [35]. In 2017, Kulkarni and

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

• ]. Recently, Sigida and co-workers reported the structure of the tetrasaccharide repeating unit of the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71T, which is composed of three α-ʟ-rhamnose units and one β-ᴅ-glucosamine moiety [21]. It also contains two O-acetyl groups which might

• -acetyl groups at the respective positions as found in the isolated O-specific polysaccharide. The formation of compound 1 was unambiguously confirmed by its NMR spectroscopic analysis [signals at δ 5.03 (br s, H-1D), 5.03 (d, J = 10.0 Hz, H-1A), 4.92 (br s, H-1C), 4.78 (br s, H-1B) in the 1H NMR and at δ

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

• glycoside; diarrhea; galactofuranose; O-specific polysaccharide; total synthesis; Introduction O-Polysaccharides are the most complex molecular systems present in the bacterial cell wall owing to the presence of various sugar residues connected through diverse glycosidic linkages. These complex structures

• and Galf. In this communication we report on the total synthesis of this pentasaccharide repeating unit of the O-specific polysaccharide in the form of its 2-aminoethyl glycoside (Figure 1) through a [3 + 2] converging strategy. The building blocks were prepared by suitable protecting group

• pentasaccharide repeating unit of the O-specific polysaccharide of Escherichia coli O132 was accomplished through a convergent [3 + 2] strategy. The target pentasaccharide was obtained as its 2-aminoethyl glycoside that offers further possibilities for conjugation with suitable aglycons without hampering the

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• , Russia N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospekt 47, Moscow 119991, Russia Chernyshevsky Saratov State University, Ulitsa Astrakhanskaya 83, Saratov 410012, Russia 10.3762/bjoc.12.62 Abstract An O-specific polysaccharide was obtained by mild acid

• , one- and two-dimensional 1H and 13C NMR spectroscopy. The following masked repeating structure of the O-specific polysaccharide was established: →3)-α-L-Rhap2Me-(1→3)-[β-D-Glcp-(1→4)]-α-D-Fucp-(1→2)-β-D-Xylp-(1→, where non-stoichiometric substituents, an O-methyl group (~45%) and a side-chain glucose

• residue (~65%), are shown in italics. Keywords: Azospirillum halopraeferens; bacterial polysaccharide structure; lipopolysaccharide; O-specific polysaccharide; Smith degradation; triflic acid solvolysis; Introduction Rhizobacteria of the genus Azospirillum are isolated from a wide variety of

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

• kidneys [10][11]. The O-specific polysaccharide of E. coli O117:K98:H4 is a linear pentasaccharide repeating unit consisting of D-galactosamine, D-glucose, D-galactose, and L-rhamnose (Figure 1) [12]. Vaccination is the recent thrust in the drug discovery program to prevent bacterial infections. Several

• pentasaccharide repeating unit of the O-specific polysaccharide of E. coli O117:K98:H4 as its 3-aminopropyl glycoside is presented herein (Figure 2). The 3-aminopropyl group would be suitable for attachment of the pentasaccharide to any surface or carrier proteins. Results and Discussion The target

• pentasaccharide repeating unit of the O-specific polysaccharide of E. coli O117:K98:H4. Structure of the synthesized pentasaccharide (1) and its precursor intermediates. Reagents and conditions: (a) (i) acetic anhydride, pyridine, room temperature, 2 h; (ii) NaBH3CN, HCl/Et2O, 5 °C, 2 h, 77% overall yield

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

• the O-specific polysaccharide of the LPS of A. brasilense Sp7 strain as its 2-aminoethyl glycoside (Figure 1) is presented herein. Results and Discussion The target tetrasaccharide 1 has been synthesized as its 2-aminoethyl glycoside (Figure 1) to facilitate its conjugation with a suitable substrate

• 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

Convergent synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9

• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2011, 7, 1182–1188, doi:10.3762/bjoc.7.137

• therapeutics than the earlier used anti-shigellosis agents [9][10]. Because of the high antigenic nature of the O-antigens, antibodies against the O-specific polysaccharide of a particular Shigella strain have the potential to control Shigella infections [11][12][13][14]. A number of reports have been cited