Clean and selective oxidation of alcohols catalyzed by ion-supported TEMPO in water

Qian, Weixing; Jin, Erlei; Bao, Weiliang; Zhang, Yongmin

doi:10.1016/j.tet.2005.10.022

Cited by 104 publications

(47 citation statements)

References 38 publications

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“…199 The bis-(acetoxy)iodobenzene moiety has been attached to an ionic liquid 200 and used with another ionic liquid containing TEMPO units for oxidation. 201 In the same type of system, an adamantane nucleus with four diacetoxyiodophenyl groups has been used as an oxidant. 41 A polystyrene-bound bis(acetoxy)iodobenzene derivative is known (see also "Experimental Procedures" section).…”

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“…However, some secondary oxidants such as bis(acetoxy)iodobenzene can be used in an entirely organic system such as methylene chloride. 192 Ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] + PF 6 − ) have been used for nitroxide-catalyzed oxidations of alcohols with hydrogen peroxide and hydrogen bromide, 268 sodium hypochlorite, 201,246 in electrochemical reactions, 294 and in aerobic oxidations with copper(I) chloride 385 .…”

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Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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The discovery in 1959 of stable nitroxide‐based free radicals such as the prototypical 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) led to their use as electron spin resonance (ESR) spin labels in chemistry, biomedicine, and materials science. These nitroxides are prepared by the oxidation of secondary amines that contain no hydrogen atoms on the alpha‐carbons. The unique redox properties of nitroxides enable their use as oxidants in organic synthesis. The varied preparation and uses of oxoammonium salts as stoichiometric oxidants for alcohols are one subject of this review. Oxoammonium ions as oxidants for alcohols have a number of advantages, for example, the method is heavy‐metal free and some of the reactions can be performed in water or aqueous mixtures. A few side reactions are associated with these oxidations. The most serious is the fast reaction of the oxoammonium ion with free amines The several ways these oxidation reactions can be carried out are discussed in detail. They are: Oxidations using stoichimetric quantities of preformed oxoammonium salts carried out in either acidic, neutral, or basic conditions; reactions in which stoichiometric quantities of oxoammonium salts are generated in situ by disproportionation of a nitroxide in the presence of a strong acid; nitroxide‐catalyzed oxidations using a secondary oxidant; efficient nitroxide‐catalyzed oxidations of primary alcohols to carboxylic acids; and oxidations of primary alcohols or hemiacetals that can lead to lactones.

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Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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“…In addition, these methods require acidic additives such as HBr, HCl, Br 2 , and chlorinated solvents in most cases. [9b, 10a-d, 11] To address the recovery issues, TEMPO was chemically anchored onto various supports such as silica, [12] organic polymers, [13] mesoporous silica, [14] functionalized ionic liquids, [15] and perfluoroalkyl systems with multiple triazole moieties. [16] Although these methods have partly addressed the recycling problem of the homogeneous TEMPO, only a few of them have shown acceptable activities in the aerobic oxidation of alcohols under transition-metal-free conditions.…”

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“…[16] Although these methods have partly addressed the recycling problem of the homogeneous TEMPO, only a few of them have shown acceptable activities in the aerobic oxidation of alcohols under transition-metal-free conditions. [14,15] Nevertheless, these methods mainly employ acidic conditions in which oxidation of acid sensitive substrates such as allylic alcohols can be problematic. Furthermore, although these protocols represent considerable advances, they still need halogen containing co-reagents, [14,15] and more importantly, the supported TEMPO catalyst is difficult to separate from the reaction solution by classical methods such as extraction, filtration, or centrifugation.…”

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A Highly Recyclable Magnetic Core‐Shell Nanoparticle‐Supported TEMPO catalyst for Efficient Metal‐ and Halogen‐Free Aerobic Oxidation of Alcohols in Water

Karimi

Farhangi

2011

Chemistry A European J

144

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Intelligente Basen: Durch Einbau eines photochromen, abschirmend wirkenden Azobenzolbausteins kann eine Piperidinbase zwischen einer sterisch abgeschirmten, inaktiven Form und einer zugänglichen, reaktiven Form hin und her geschaltet werden (siehe Schema; grau C, weiß H, rot O, blau N). Es ist daher möglich, die Basizität im Grundzustand und somit auch die Reaktivität in der allgemeinen Basenkatalyse von außen durch Licht zu steuern.

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“…[14][15][16][17][18][19][20][21][22][23] Regarding this interest, we have recently reported a versatile and clean method based on the use of the adamantanetype recyclable hypervalent iodine reagent 1 [24][25][26] (Fig. 1) for the organocatalytic oxidation of alcohols to aldehydes and ketones.…”

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Speedy and Clean Hypervalent Iodine/Nitroxyl Radical Mediated Oxidation of Alcohols Using Recyclable Adamantane Reagent with Highly Active 2-Azaadamantane-<i>N</i>-oxyl Organocatalyst

Dohi

Kamitanaka

Mochizuki

et al. 2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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By utilizing a specific solvent and highly active 2-azaadamantane-N-oxyl (AZADO) as an organocatalyst, we have improved the recycling protocol of the adamatane reagent 1 to be faster and more operationally simple for the hypervalent iodine/nitroxyl radical mediated alcohol oxidation. This very mild system can efficiently mediate the oxidation of a range of alcohols to carbonyl compounds with a broad substrate scope, and after the reactions, the reduced adamantane tetraiodide 1′, which automatically precipitated from the reaction mixtures as the reactions progresses, could be directly recovered by filtration.Key words alcohol oxidation; speedy process; recycling; hypervalent iodine reagent; nitroxyl radicalThe development of an efficient and clean method for the oxidation of alcohol functionalities to carbonyl groups remains an important topic widely investigated in modern synthetic chemistry.1-3) Among the present methods, the combination of the hypervalent iodine reagent [4][5][6][7][8] and nitroxyl radical catalyst, 9,10) which was first suggested by Piancatelli and Margarita's research group in the literature, 11) has gained particular attention in the past decades as a mild and metal-free versatile oxidation system. Due to the salient features of the catalytic conditions as well as the exclusive chemoselectivity toward alcohols in the presence of many oxidation-sensitive functional groups, this mild organocatalytic system has been frequently used for the selective oxidation of alcohol groups in complex molecules, [4][5][6][7][8] as represented by the early examples which appeared in the total synthesis of natural products, such as discodermolide and leucascandrolide A.12,13) Moreover, significant advances have been developed to date for the reagent and catalyst recycling, making the strategy and method even more attractive. [14][15][16][17][18][19][20][21][22][23] Regarding this interest, we have recently reported a versatile and clean method based on the use of the adamantanetype recyclable hypervalent iodine reagent 1 [24][25][26] (Fig. 1) for the organocatalytic oxidation of alcohols to aldehydes and ketones.27,28) The well-defined tetrahedral structure and sufficient interatomic distances between the iodine(III) sites in the molecule of the adamantane 1 are due to its higher reactivity and good solubility in solvents compared to the conventional polymer-supported reagents. Also, it is very stable under severe oxidative conditions, and the degradation of the molecule did not occur even after many recyclings. Furthermore, the reagent could be nearly quantitatively recovered after the reactions by utilizing the insolubility of the formed tetraiodide 1′ in a polar solvent, specifically, methanol. Based on these significant advantages, the adamantane reagent 1 would serve as a recyclable and greener alternative to conventionally-used hypervalent iodine reagents, and mediate many types of oxidation reactions with efficiencies similar to those of phenyliodine diacetate (PIDA), [29][30][31][32][33][34][35][36] w...

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Clean and selective oxidation of alcohols catalyzed by ion-supported TEMPO in water

Cited by 104 publications

References 38 publications

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

A Highly Recyclable Magnetic Core‐Shell Nanoparticle‐Supported TEMPO catalyst for Efficient Metal‐ and Halogen‐Free Aerobic Oxidation of Alcohols in Water

Speedy and Clean Hypervalent Iodine/Nitroxyl Radical Mediated Oxidation of Alcohols Using Recyclable Adamantane Reagent with Highly Active 2-Azaadamantane-<i>N</i>-oxyl Organocatalyst

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