Selective oxidation of monosaccharide derivatives to uronic acids

Davis, Nicola J.; Flitsch, Sabine L.

doi:10.1016/s0040-4039(00)77522-8

Cited by 231 publications

(111 citation statements)

References 10 publications

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“…In contrast to literature results, 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)/NaOCl [21,[49][50][51][52][53][54][55][56] or TEMPO/iodobenzene diacetate [57] oxidation led to a mixture of partially oxidized products, which is probably due to the hydrophobic nature of our fully protected oligosaccharides. [58] A two-step process of Dess-Martin oxidation and subsequent treatment with NaClO 2 [59] also gave inconsistent results.…”

Section: Deprotection Of Shacontrasting

confidence: 99%

Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides

Huang

2006

Chemistry A European J

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Highly efficient syntheses of hyaluronic acid oligosaccharides have been accomplished through the pre-activation based iterative one-pot strategy. A series of oligosaccharides ranging from di-to hexasaccharides were rapidly assembled using only near stoichiometric amounts of the building blocks without aglycon adjustment or purifications of intermediate oligosaccharides. Deprotection and oxidation protocols were developed for protective group removal and oxidation-state adjustment. The availability of such structurally well defined synthetic hyaluronic acid oligosaccharides will greatly facilitate the establishment of detailed structure-function relationships.

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Section: Deprotection Of Shacontrasting

confidence: 99%

Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides

Huang

2006

Chemistry A European J

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“…The process of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical oxidizing the primary alcohol groups of monosaccharides to carboxylic groups was reported by Davis and Flitsch in 1993 which has become one of the most extensive research topics in the area of oxidation of cellulose [202]. The typical oxidation system for cellulose is TEMPO/NaBr/NaClO [203], which has been extensively used for the pretreatment of raw cellulose materials before mechanical disintegration [22,189,204,205].…”

Section: Tempo Oxidationmentioning

confidence: 99%

Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

Xie

Yang

2018

International Journal of Polymer Science

207

128

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The recent strategies in preparation of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) were described. CNCs and CNFs are two types of nanocelluloses (NCs), and they possess various superior properties, such as large specific surface area, high tensile strength and stiffness, low density, and low thermal expansion coefficient. Due to various applications in biomedical engineering, food, sensor, packaging, and so on, there are many studies conducted on CNCs and CNFs. In this review, various methods of preparation of CNCs and CNFs are summarized, including mechanical, chemical, and biological methods. The methods of pretreatment of cellulose are described in view of the benefits to fibrillation.

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“…[12,65,75,76] For example, methyl a-d-glucopyranoside afforded methyl a-d-glucopyranosiduronate [Equation (11)] in 90% yield. [77] ð11Þ 7 Ruthenium/TEMPO-Catalyzed Aerobic Oxidation of Alcohols…”

Section: Reviewsmentioning

confidence: 99%

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

2004

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The use of nitroxyl radicals, alone or in combination with transition metals, as catalysts in oxidation processes is reviewed from both a synthetic and a mechanistic viewpoint. Two extremes of reactivity can be distinguished: stable (persistent) dialkylnitroxyls, such as the archetypal TEMPO, and reactive diacylnitroxyls, derived from N-hydroxy imides, such as N-hydroxyphthalimide (NHPI). The different types of reactivity observed are rationalized by considering the bond dissociation energies (BDEs) of the respective N-hydroxy precursors, substrates and reaction intermediates. Reactive diacylnitroxyl radicals are generated in situ from the corresponding N-hydroxy compound. The protagonist, NHPI, catalyzes a wide variety of free radical autoxidations, improving both activities and selectivities by increasing the rate of chain propagation and/or decreasing the rate of chain termination. In the absence of metal co-catalysts improved conversions and selectivities are obtained in the autoxidation of hydrocarbons to the corresponding alkyl hydroperoxides. For example, cyclohexylbenzene afforded the 1-hydroperoxide in 97.6% selectivity at 32% conversion when the autoxidation was performed in the presence of 0.5 mol % NHPI, and the product hydroperoxide as initiator, at 100 8C. This forms the basis for a potential coproduct-free route from benzene to phenol. In combination with transition metal co-catalysts, notably cobalt, NHPI and related compounds, such as N-hydroxysaccharin NHS, afford effective catalytic systems for the effective autoxidation of hydrocarbons, e.g., toluenes to carboxylic acids, under mild conditions. In the case of the less reactive cycloalkanes, NHS proved to be a more active catalyst than NHPI which is attributed to the higher reactivity of the intermediate nitroxyl radical, resulting from the replacement of a carbonyl group in NHPI by the more strongly electron-attracting sulfonyl group. Stable dialkylnitroxyl radicals, exemplified by TEMPO, catalyze oxidations of, e.g., alcohols, with single oxygen donors such as hypochlorite and organic peracids. The reactions involve the intermediate formation of the corresponding oxoammonium cation as the active oxidant. Alternatively, in conjunction with transition metals, notably ruthenium and copper, they catalyze aerobic oxidations of alcohols. These reactions involve metal-centered dehydrogenations and the role of the TEMPO is to facilitate regeneration of the catalyst (Ru and Cu) and oxidation of the alcohol (Cu) via hydrogen abstraction or one-electron oxidation processes. Detailed mechanistic investigations, including kinetic isotope effects, revealed that oxoammonium cations are not involved as intermediates in these reactions. In contrast, oxoammonium cations are involved in the aerobic oxidation of alcohols catalyzed by the copper-dependent oxidase, laccase, in combination with TEMPO. This different mechanistic pathway is attributed to the much higher redox potential of the copper(II) in the enzyme. Similarly, N-hydroxy compounds such as ...

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Selective oxidation of monosaccharide derivatives to uronic acids

Cited by 231 publications

References 10 publications

Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides

Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides

Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

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