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

• from E. coli O132 is accomplished in the form of its 2-aminoethyl glycoside. The 2-aminoethyl glycoside is particularly important as it allows further glycoconjugate formation utilizing the terminal amine without affecting the stereochemistry of the reducing end. The target was achieved through a [3

• 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

• manipulations on the commercially available monosaccharides and stereoselective chemical glycosylations. The 2-aminoethyl glycoside at the reducing end will facilitate further glycoconjugate formation without hampering the stereochemistry of the anomeric center. We have used similar glycosides in case of other

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

• the biofilm producing polysaccharide secreted by K. pneumoniae. A convergent synthesis of a pentasaccharide as its 2-aminoethyl glycoside containing a β-D-mannosidic moiety and a α-D-glucuronic acid moiety is presented herein. The presence of a 2-aminoethyl group at the reducing end of the

• pentasaccharide may provide ready availability of an amino functionality to expedite the conjugation of the pentasaccharide with an appropriate protein without affecting the sugar rings in the molecule [12][13]. Results and Discussion The target pentasaccharide as its 2-aminoethyl glycoside 1 was synthesized

• reaction conditions furnished the D-glucuronic acid containing pentasaccharide derivative, which on global deprotection under hydrogenolysis in the presence of Pearlman’s catalyst [40] afforded the target pentasaccharide as its 2-aminoethyl glycoside 1 in 61% yield (Scheme 4). Conclusion In summary, a

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 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

• 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