Synthesis of the hexasaccharide repeating unit corresponding to the cell wall lipopolysaccharide of Azospirillum irakense KBC1

Total Synthesis of Clostrienose

This paper considers the total synthesis of a cellular differentiation regulator of Clostridium acetobutylicum, clostrienose, which is a unique fatty-acid glycosyl ester consisting of clostrienoic acid, (3R,5E,8E,10E)-3-hydroxy-tetradeca-5,8,10-trienoic acid and α-d-galactofuranosyl-(1 → 2)-α-l-rhamnose. The key features of our synthesis include stereoselective construction of a skipped-triene system in clostrienoic acid and its esterification with a disaccharide residue. The partially protected clostrienoic acid employed for the coupling also served for the preparation of l-rhamnosyl clostrienoate, thus leading to confirmation of the proposed structure unambiguously.

Synthesis of a hexasaccharide repeating unit of the cell wall polysaccharide of Bifidobacterium animalis subsp. lactis LKM512

A convergent synthesis of the hexasaccharide as its 2-aminoethyl glycoside corresponding to the repeating unit of the cell wall polysaccharide of Bifidobacterium animalis subsp. lactis LKM512 has been achieved applying a [4 + 2] glycosylation strategy. The disaccharide thioglycoside donor was prepared by combining a d-galactofuranosyl thioglycoside with another l-rhamnosyl thioglycoside acceptor. The yields of the individual glycosylation steps were highly satisfactory with excellent stereo outcome. An α-glycosidic linkage of the d-galactofuranosyl moiety in the hexasaccharide was achieved in very good yield.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

Synthesis of an Aminooxy Derivative of the Trisaccharide Globotriose Gb3

The synthesis of α-aminooxy trisaccharide moiety [α-d-Gal-(1,4)-β-d-Gal-(1,4)-β-d-Glc-α-aminooxy], related to the cell surface globotriaosylceramide (Gb3) receptor of the B subunit of the AB₅ Shiga toxin of Shigella dysenteriae, has been synthesized for the first time in 11 steps with a 15% overall isolated yield. A highlight of this work entails utilizing chemically compatible synthetic transformations, including those related to glycosylation, incorporative of the succinimidyl moiety as a precursor to the aminooxy Gb3 derivative. The fully deprotected trisaccharide aminooxy compound was reacted with a carbonyl compound leading to oxime formation in quantitative yield underscoring the importance for future glyco-conjugations.

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

A straightforward convergent synthesis has been carried out for the tetrasaccharide repeating unit of the O-specific cell wall lipopolysaccharide of the strain Sp7 of Azospirillum brasilense. The target tetrasaccharide has been synthesized from suitably protected monosaccharide intermediates in 42% overall yield in seven steps by using a [2 + 2] block glycosylation approach.

Glycosylation studies on conformationally restricted 3,5-O-(di-tert-butylsilylene)-D-galactofuranosyl trichloroacetimidate donors for 1,2-cis α-D-galactofuranosylation

Conformationally restricted 3,5-O-di-tert-butylsilylene-D-galactofuranosyl trichloroacetimidate donors were synthesized from allyl α-D-galactofuranoside for the construction of 1,2-cis α-D-galactofuranosyl linkages. Glycosylation reactions were performed with several acceptors, including D-galactono-1,4-lactone, D-rhamnopyranosyl, and D-mannopyranosyl derivatives. The influence of the temperature and the reaction solvents was evaluated, as well as the 6-O-substitution pattern of the donor. The higher α-selectivities were obtained at -78 °C in diethyl ether as solvent. 6-O-Acetyl substitution on constrained donor increased the α-selectivity compared to the 6-O-benzyl substitution. Almost no selectivities were observed in the non-participating solvent CH(2)Cl(2). In contrast, ethereal solvents enhanced the α-selectivity suggesting a participating effect in the reaction intermediate.