- Synthesis of glycosyl fluorides from (phenylthio)glycosides using IF5-pyridine-HF
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IF5-pyridine-HF, an air- and moisture-stable fluorinating reagent, was applied to the synthesis of glycosyl fluorides from (phenylthio)glycosides. Common protecting groups of alcohol and diol can tolerate the reaction conditions performed, and therefore, the present method is applicable to the synthesis of various glycosyl fluorides.
- Kunigami, Masataka,Hara, Shoji
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- Synthesis and use of mechanism-based protein-profiling probes for retaining β-D-glucosaminidases facilitate identification of Pseudomonas aeruginosa NagZ
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The NagZ class of retaining exo-glucosaminidases play a critical role in peptidoglycan recycling in Gram-negative bacteria and the induction of resistance to β-lactams. Here we describe the concise synthesis of 2-azidoacetyl-2-deoxy-5-fluoro-β-D-glucopyranosyl fluoride as an activity-based proteomics probe for profiling these exo-glycosidases. This active-site directed reagent covalently inactivates this class of retaining N-acetylglucosaminidases with exquisite selectivity by stabilizing the glycosyl-enzyme intermediate. Inactivated Vibrio cholerae NagZ can be elaborated with biotin or a FLAG-peptide epitope using the Staudinger ligation or the Sharpless-Meldal click reaction and detected at nanogram levels. This ABPP enabled the profiling of the Pseudomonas aeruginosa proteome and identification at endogenous levels of a tagged protein with properties consistent with those of PA3005. Cloning of the gene encoding this hypothetical protein and biochemical characterization enabled unambiguous assignment of this hypothetical protein as a NagZ. The identification and cloning of this NagZ may facilitate the development of strategies to circumvent resistance to β-lactams in this human pathogen. As well, this general strategy, involving such 5-fluoro inactivators, may prove to be of general use for profiling proteomes and identifying glycoside hydrolases of medical importance or having desirable properties for biotechnology.
- Stubbs, Keith A.,Scaffidi, Adrian,Debowski, Aleksandra W.,Mark, Brian L.,Stick, Robert V.,Vocadlo, David J.
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p. 327 - 335
(2008/10/09)
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- Preparation of glucosaminyl muramic acid derivatives
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The present invention provides a method for the preparation of disaccharides, such as glucosaminyl muramic acids peptides and derivatives. The method includes condensing a protected muramic acid ester with a 1-organothio- or 1-fluoroglucosamine derivative in the presence of a suitable promoter to produce a protected glucosaminyl muramic acid ester. The protected glucosaminyl muramic acid ester may be used to prepare disaccharide peptides, such as N-acetylglucosaminyl-N-acetylmuramyl dipeptides, which have demonstrated immunological activity. Protected muramic acid esters and 1-organothio- or 1-fluoro- glucosamine compounds which may be employed as intermediates in the method are also provided.
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- Synthesis of the root nodule-inducing factor NodRm-IV(C16:2,S) of rhizobium meliloti and related compounds
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Nod factors NodRm-IV(RCO,S) that carry natural as well as unnatural fatty acids were synthesized in a stereocontrolled manner.
- Ikeshita, Shinji,Sakamoto, Akio,Nakahara, Yuko,Nakahara, Yoshiaki,Ogawa, Tomoya
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p. 3123 - 3126
(2007/10/02)
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- A new method of anomeric protection and activation based on the conversion of glycosyl azides into glycosyl fluorides
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Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic diol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides. Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic idol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides.
- Broder,Kunz
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p. 221 - 241
(2007/10/02)
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- Stereoselective Synthesis of Glycosides and Anomeric Azides of Glucosamine
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The β-azide of O-acetyl protected N-acetyl glucosamine is efficiently accessible via a phase-transfer-catalyzed reaction of the corresponding glycosyl chloride with sodium azide.The azido group revealed to be a useful anomeric protection for modifications of the protecting group pattern of the glucosamine unit.Exchange of the O-acyl groups by 4-methoxybenzylidene and 4-methoxybenzyl (Mpm) protection delivered regioselectively blocked glucosaminyl azide derivatives.In contrast, the N-phthaloyl protected glucosaminyl azide was obtained quantitatively from the corresponding glycosyl fluoride via a boron trifluoride-promoted reaction with trimethylsilyl azide.N-Phthaloyl glucosaminyl fluoride was also revealed to be useful in the synthesis of β-glucosamine glycosides and saccharides.Chitobiosyl azide 21 carrying a selectively removable 6-O-Mpm protection was synthesized from the O-acetyl protected N-phthaloyl glucosaminyl bromide and N-acetylglucosaminyl azide 13 as an acceptor selectively deblocked at O-4.
- Unverzagt, Carlo,Kunz, Horst
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p. 570 - 578
(2007/10/02)
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