Zemplén Deacetylation

doi:10.1002/9780470638859.conrr691

Cited by 10 publications

(5 citation statements)

References 83 publications

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“…Finally, the functional group transformations and the global deprotection of the pentasaccharide 2 lead to the target molecule 1 , which is delineated in Scheme . Protected pentasaccharide 2 was subjected to a series of functional group transformations: (a) conversion of the N -phthaloyl group to an acetamido group by ethylenediamine catalyzed removal of the N -phthaloyl group followed by N - and O -acetylation using acetic anhydride and pyridine; (b) one-pot conversion of azido to the N -acetate group using thioacetic acid; (c) removal of the benzyl ether using Pd(OH) 2 /C and H 2 ; and (d) deacetylation by NaOMe in MeOH furnished the target pentasaccharide 1 in a 64% overall yield.…”

Section: Resultssupporting

confidence: 90%

“…Formation of compound 23 was confirmed by the appearance of NMR signals at δ 5.42 (s, PhC H ), 5.82 (d, J = 3.6 Hz, 1H, H-1 B ) in the 1 H NMR and δ 101.6 (Ph C H), 97.9 (C-1 B ) in the 13 C NMR spectra. The acetate group in disaccharide 23 was selectively de-acetylated quantitatively by the Zemplén reaction to afford disaccharide acceptor 6 .…”

Section: Resultsmentioning

confidence: 99%

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Total Synthesis of 6-Deoxy-l-talose Containing a Pentasaccharide Repeating Unit of Acinetobacter baumannii K11 Capsular Polysaccharides

Bharali

Santra

2023

J. Org. Chem.

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Herein, we report a concise synthetic approach for the first total synthesis of a pentasaccharide repeating unit of Acinetobacter baumannii K11 capsular polysaccharides containing a rare sugar 6-deoxy-L-talose. The pentasaccharide was synthesized in a convergent manner using a [3 + 2] block glycosylation strategy. During this synthetic strive, we used a 2,2,2trichloroethoxycarbonyl (Troc)-protected monosaccharide unit to achieve a high yield during the glycosylation to synthesize a trisaccharide, and chemoselective deprotection of the Troc group from the trisaccharide was carried out under a mild, pH-neutral condition, keeping the O-glycosidic bond, azido, and acid/base sensitive group intact. A thiotolylglycoside disaccharide donor containing 6-deoxy-L-talose was synthesized for the first time by the armed-disarmed glycosylation method between two thiotolylglycosides.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Total Synthesis of 6-Deoxy-l-talose Containing a Pentasaccharide Repeating Unit of Acinetobacter baumannii K11 Capsular Polysaccharides

Bharali

Santra

2023

J. Org. Chem.

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“…Bipy Glu‑Ac and Bipy Gal‑Ac were then reacted with [{Ir(F 2 ppy) 2 (μ–Cl)} 2 ] [F 2 ppy = cyclometallated anion of 2-(2,4-difluorophenyl)pyridine] to afford mononuclear Ir Glu‑Ac ( 16 ) and Ir Gal‑Ac ( 17 ) as their chloride salts, which were purified by size-exclusion chromatography on Sephadex LH-20. Finally, deprotection under Zemplén conditionsanhydrous MeOH and catalytic NaOMeafforded the desired complexes Ir Glu ( 18 ) and Ir Gal ( 19 ). This deprotection step requires neutralization using the acidic ion-exchange resin Dowex 50W X8, and we found that leaving this step for too long resulted in the cation of the deprotected complexes Ir Glu and Ir Gal adhering to the resin, as shown by the loss of complex from solution and the appearance of green phosphorescence from the Dowex resin.…”

Section: Resultsmentioning

confidence: 99%

Programmable Monodisperse Glyco-Multivalency Using Self-Assembled Coordination Cages as Scaffolds

Pritchard,

Ligorio,

Jackson

et al. 2023

ACS Appl. Mater. Interfaces

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The multivalent presentation of glycans leads to enhanced binding avidity to lectins due to the cluster glycoside effect. Most materials used as scaffolds for multivalent glycan arrays, such as polymers or nanoparticles, have intrinsic dispersity: meaning that in any sample, a range of valencies are presented and it is not possible to determine which fraction(s) are responsible for binding. The intrinsic dispersity of many multivalent glycan scaffolds also limits their reproducibility and predictability. Here we make use of the structurally programmable nature of self-assembled metal coordination cages, with polyhedral metal-ion cores supporting ligand arrays of predictable sizes, to assemble a 16-membered library of perfectly monodisperse glycoclusters displaying valencies from 2 to 24 through a careful choice of ligand/metal combinations. Mono- and trisaccharides are introduced into these clusters, showing that the synthetic route is tolerant of biologically relevant glycans, including sialic acids. The cluster series demonstrates increased binding to a range of lectins as the number of glycans increases. This strategy offers an alternative to current glycomaterials for control of the valency of three-dimensional (3-D) glycan arrays, and may find application across sensing, imaging, and basic biology.

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“…Zheng et al demonstrated that a homopolymer of 2-(diethylamino)-ethyl methacrylate prepared by Cu(0) mediated reversible deactivation radical polymerization can be modified to incorporate pendant saccharide groups. First, saccharides are modified to make them suitable alkylating agents (Scheme a) by acetylating the hydroxyl groups with acetic anhydride in the presence of iodine, reacting with one equivalent of α,ω-dibromoalkanol in trifluoroborane in diethyl ether, and then removing remaining acetyl groups via the Zemplén deacetylation (treatment in methanol with a catalytic amount of sodium methoxide). Then the saccharide alkylating agent is reacted with the polymer to quaternize the pendant amines (Scheme b).…”

Section: Synthesesmentioning

confidence: 99%

Polymerized and Colloidal Ionic Liquids─Syntheses and Applications

Li,

Yan,

Texter

2024

Chem. Rev.

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The breadth and importance of polymerized ionic liquids (PILs) are steadily expanding, and this review updates advances and trends in syntheses, properties, and applications over the past five to six years. We begin with an historical overview of the genesis and growth of the PIL field as a subset of materials science. The genesis of ionic liquids (ILs) over nano to meso lengthscales exhibiting 0D, 1D, 2D, and 3D topologies defines colloidal ionic liquids, CILs, which compose a subclass of PILs and provide a synthetic bridge between IL monomers (ILMs) and micro to macroscale PIL materials. The second focus of this review addresses design and syntheses of ILMs and their polymerization reactions to yield PILs and PIL-based materials. A burgeoning diversity of ILMs reflects increasing use of nonimidazolium nuclei and an expanding use of step-growth chemistries in synthesizing PIL materials. Radical chain polymerization remains a primary method of making PILs and reflects an increasing use of controlled polymerization methods.Step-growth chemistries used in creating some CILs utilize extensive cross-linking. This cross-linking is enabled by incorporating reactive functionalities in CILs and PILs, and some of these CILs and PILs may be viewed as exotic cross-linking agents. The third part of this update focuses upon some advances in key properties, including molecular weight, thermal properties, rheology, ion transport, self-healing, and stimuli-responsiveness. Glass transitions, critical solution temperatures, and liquidity are key thermal properties that tie to PIL rheology and viscoelasticity. These properties in turn modulate mechanical properties and ion transport, which are foundational in increasing applications of PILs. Cross-linking in gelation and ionogels and reversible step-growth chemistries are essential for self-healing PILs. Stimuli-responsiveness distinguishes PILs from many other classes of polymers, and it emphasizes the importance of segmentally controlling and tuning solvation in CILs and PILs. The fourth part of this review addresses development of applications, and the diverse scope of such applications supports the increasing importance of PILs in materials science. Adhesion applications are supported by ionogel properties, especially crosslinking and solvation tunable interactions with adjacent phases. Antimicrobial and antifouling applications are consequences of the cationic nature of PILs. Similarly, emulsion and dispersion applications rely on tunable solvation of functional groups and on how such groups interact with continuous phases and substrates. Catalysis is another significant application, and this is an historical tie between ILs and PILs. This component also provides a connection to diverse and porous carbon phases templated by PILs that are catalysts or serve as supports for catalysts. Devices, including sensors and actuators, also rely on solvation tuning and stimuliresponsiveness that include photo and electrochemical stimuli. We conclude our view of applications with 3D printi...

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Zemplén Deacetylation

Cited by 10 publications

References 83 publications

Total Synthesis of 6-Deoxy-l-talose Containing a Pentasaccharide Repeating Unit of Acinetobacter baumannii K11 Capsular Polysaccharides

Total Synthesis of 6-Deoxy-l-talose Containing a Pentasaccharide Repeating Unit of Acinetobacter baumannii K11 Capsular Polysaccharides

Programmable Monodisperse Glyco-Multivalency Using Self-Assembled Coordination Cages as Scaffolds

Polymerized and Colloidal Ionic Liquids─Syntheses and Applications

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