First Synthesis of <i>Bacillus cereus</i> Ch HF-PS Cell Wall Trisaccharide Repeating Unit

It was established that para-substituted benzyl ether protecting groups affect the reactivity of glycosyl donors of the thioglycoside type with the N-iodosuccinimide/triflic acid promoter system. Having electron donating p-methoxybenzyl ether (PMB) groups increased the reactivity of the donor in comparison to having electron withdrawing p-chloro (PClB) or p-cyanobenzyl ether (PCNB) protecting groups, which decreased the reactivity of the glycosyl donor relative to the parent benzyl ether (Bn) protected glycosyl donor. These findings were used to perform the first armed-disarmed coupling between two benzylated glucosyl donors by tuning their reactivity. In addition, the present work describes a highly efficient palladium catalyzed multiple cyanation and methoxylation of p-chlorobenzyl protected thioglycosides. The results of this paper regarding both the different electron withdrawing properties of various benzyl ethers and the efficient and multiple protecting group transformations are applicable in general organic chemistry and not restricted to carbohydrate chemistry.

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“…HRMS (ES): Calcd for C 40 H 40 O 5 SNH 4 + 650.2935; found 650.2943. Spectral values were in accordance with those reported in ref .…”

Section: Methodssupporting

confidence: 91%

Remote Electronic Effects by Ether Protecting Groups Fine-Tune Glycosyl Donor Reactivity

2016

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“…Since the relative reactivity value (RRV; 28.6) of the 2‐NHTroc‐ d ‐glucosamine donor is higher than that (1.0–3.5) of the 2‐NPhth‐ d ‐glucosamine donor, Troc was chosen as an alternative protecting group for the C2 amino group of Le y tetrasaccharide. Selective removal of the Phth group using ethylene diamine in n BuOH at an elevated temperature (95 °C) and subsequent treatment with TrocCl in pyridine furnished the the tetrasaccharide 38 . Glycosylation of 38 and 36 under TfOH and NIS activation at −20 °C afforded the β‐linked product 39 in 70 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…[29] Since the relative reactivity value (RRV; 28.6) of the 2-NHTroc-d-glucosamine donor is higher than that (1.0-3.5) of the 2-NPhth-d-glucosamine donor, [29] Tr oc was chosen as an alternative protecting group for the C2 amino group of Le y tetrasaccharide. Selective removal of the Phth group using ethylene diamine in nBuOH at an elevated temperature (95 8 8C) [39] and subsequent treatment with TrocCl in pyridine furnished the the tetrasaccharide 38.G lycosylation of 38 and 36 under TfOH and NIS activation at À20 8 8Cafforded the b-linked product 39 in 70 %yield. Partial cleavage of Tr oc under TBAF conditions forced us to choose HF-pyridine to remove anomeric TBS group.T he obtained hemiacetal was transformed into the corresponding trifluoroacetimidate 40 in 42 %o verall yield.…”

Section: Synthesis Of the Heptoglycan-octasaccharidementioning

confidence: 99%

Chemical Synthesis and Immunological Evaluation of Helicobacter pylori Serotype O6 Tridecasaccharide O‐Antigen Containing a dd‐Heptoglycan

Tian

Qin

et al. 2020

Angewandte Chemie

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The development of glycoconjugate vaccines against Helicobacter pylori is challenging. An exact epitope of the H. pylori lipo‐polysaccharide (LPS) O‐antigens that contain Lewis determinant oligosaccharides and unique dd‐heptoglycans has not yet been identified. Reported here is the first total synthesis of H. pylori serotype O6 tridecasaccharide O‐antigen containing a terminal Ley tetrasaccharide, a unique α‐(1→3)‐, α‐(1→6)‐, and α‐(1→2)‐linked heptoglycan, and a β‐d‐galactose connector, by an [(2×1)+(3+8)] assembly sequence. Seven oligosaccharides covering different portions of the entire O‐antigen were prepared for immunological investigations with a particular focus on elucidation of the roles of the dd‐heptoglycan and Ley tetrasaccharide. Glycan microarray analysis of sera from rabbits immunized with isolated serotype O6 LPS revealed a humoral immune response to the α‐(1→3)‐linked heptoglycan, a key motif for designing glycoconjugate vaccines for H. pylori serotype O6.

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“…Kulkarni and co-workers reported its first total synthesis in 2014 [ 115 ]. Trisaccharide 226 was assembled in [2 + 1] glycosylation manner as outlined in Scheme 25 .…”

Section: Bacillus Cereus Ch Hf-psmentioning

confidence: 99%

Chemical Synthesis of Rare, Deoxy-Amino Sugars Containing Bacterial Glycoconjugates as Potential Vaccine Candidates

Behera

Kulkarni

2018

Molecules

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Bacteria often contain rare deoxy amino sugars which are absent in the host cells. This structural difference can be harnessed for the development of vaccines. Over the last fifteen years, remarkable progress has been made toward the development of novel and efficient protocols for obtaining the rare sugar building blocks and their stereoselective assembly to construct conjugation ready bacterial glycans. In this review, we discuss the total synthesis of a variety of rare sugar containing bacterial glycoconjugates which are potential vaccine candidates.

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First Synthesis of Bacillus cereus Ch HF-PS Cell Wall Trisaccharide Repeating Unit

Cited by 25 publications

References 32 publications

Remote Electronic Effects by Ether Protecting Groups Fine-Tune Glycosyl Donor Reactivity

Remote Electronic Effects by Ether Protecting Groups Fine-Tune Glycosyl Donor Reactivity

Chemical Synthesis and Immunological Evaluation of Helicobacter pylori Serotype O6 Tridecasaccharide O‐Antigen Containing a dd‐Heptoglycan

Chemical Synthesis of Rare, Deoxy-Amino Sugars Containing Bacterial Glycoconjugates as Potential Vaccine Candidates

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