Eco-friendly copper sulfate-catalyzed oxidation of amines to imines by hydrogen peroxide in water

Marui, Kuniaki; Nomoto, Akihiro; Ueshima, Michio; Ogawa, Akira

doi:10.1016/j.tetlet.2015.01.090

Cited by 24 publications

(18 citation statements)

References 49 publications

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“…Recently, we have reported a series of eco-friendly oxidations of alcohols and amines using metal catalysts: for example, the vanadium complex-catalyzed oxidation of benzyl alcohols 25 or benzylamines with atmospheric O 2 in water or ionic liquid 26 and the copper sulfate-catalyzed oxidation of amines with H 2 O 2 in water 27 (Scheme 1, eqs 1 and 2, respectively). In the former catalytic oxidation, 3-hydroxypicolinic acid (H 2 hpic) or its analogues were used as ligands for oxovanadium complexes.…”

Section: Introductionmentioning

confidence: 99%

Metal-Free Oxidative Coupling of Benzylamines to Imines under an Oxygen Atmosphere Promoted Using Salicylic Acid Derivatives as Organocatalysts

et al. 2016

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The oxidative coupling of benzylamines proceeds efficiently using salicylic acid derivatives as organocatalysts under an oxygen atmosphere, affording the corresponding N -benzylidenebenzylamines in high yields. Electron-rich salicylic acid derivatives such as 4,6-dimethoxysalicylic acid and 4,6-dihydroxysalicylic acid exhibit excellent catalytic activities for the oxidative coupling of benzylamines to give the corresponding imines. This amine oxidation can also be applied to the synthesis of nitrogen-containing heterocycles such as benzimidazole derivatives. Furthermore, to recycle the catalyst, silica gel supported with 4.7 wt % of 4,6-dihydroxysalicylic acid is prepared, which acts as a recyclable catalyst, oxidizing benzylamine to imine four times successfully.

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Section: Introductionmentioning

confidence: 99%

Metal-Free Oxidative Coupling of Benzylamines to Imines under an Oxygen Atmosphere Promoted Using Salicylic Acid Derivatives as Organocatalysts

et al. 2016

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“…Prolonging the reaction time successfully facilitated atmospheric oxidation of benzylamine (1a) to afford 2a in 86% yield (entry 10). Next, other vanadium catalysts were examined for the oxidation of amines under pressurized or atmospheric oxygen (entries [11][12][13][14][15][16][17][18]. Among the catalysts examined, the vanadium complex [VO(Hhpic) 2 ] exhibited the best results (entry 10).…”

Section: Akihiro Nomoto Was Born Inmentioning

confidence: 99%

“…Although most metal sulfates exhibited minimal catalytic activities in the oxidation (the yields of 2a were 1-3%), copper(II) sulfate catalyzed the reaction efficiently, and 2a was obtained in a high yield (entry 4). 16,17 A negligible yield of imine 2a was obtained when no catalyst was used (Table 5, entry 5). Various copper(I) and copper(II) salts were examined in the oxidation, giving imine 2a in poor to high yields, with recovery of the starting amine (entries 6-11).…”

Section: Feature Syn Thesismentioning

confidence: 99%

“…In general, aliphatic amines are oxidized less efficiently than the corresponding aromatic amines. Very interestingly, this mild oxidation method could, nevertheless, be applied successfully to aliphatic amines; aliphatic primary amines 1l, 1m, and 1n were also efficiently oxidized to the corresponding imines 2l, 2m, and 2n (Table 6, entries [16][17][18].…”

Section: Syn Thesismentioning

confidence: 99%

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Green Oxidation of Amines to Imines Based on the Development of Novel Catalytic Systems Using Molecular Oxygen or Hydrogen Peroxide

2015

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Amines are transformed into the corresponding imines by environmentally benign catalytic oxidation reactions. Gaseous oxygen or hydrogen peroxide is used as the oxidant, and water is the only byproduct. When a vanadium complex is used as the catalyst in an ionic liquid, the amine oxidation successfully proceeds with recycling of the catalyst. Amine oxidation with hydrogen peroxide as an oxidant in water is also attained by using copper(II) sulfate as catalyst. In addition, photoinduced oxidation of amines to imines is conducted by using oxygen as the oxidant in the presence of a zinc-chlorin complex as catalyst.

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“…Recently, we successfully developed a series of transition-metal-catalyzed or organocatalytic systems for the oxidation of alcohols 7 and amines 8 using molecular oxygen or aqueous hydrogen peroxide, wherein oxidovanadium complexes 7 and copper sulfate, 8b 8c were found to act as an oxidation catalyst even in water. In addition, we developed a Pt-C/AgO/CuO catalytic system, which catalyzes the oxidation of HMF to FDCA using O 2 in water.…”

Section: Introductionmentioning

confidence: 99%

Au/Ag/Cu-Mixed Catalysts for the Eco-Friendly Oxidation of 5-Hydroxymethylfurfural and Related Compounds to Carboxylic Acids under Atmospheric Oxygen in Water

et al. 2020

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A green method for the oxidation of alcohols to carboxylic acids was developed using a novel co-catalytic system based on gold, silver, and copper catalysts. This reaction system was conducted under atmospheric oxygen in water and mild conditions to selectively oxidize 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, as a building block for polyethylene furanoate, which is a 100% bio-based, future alternative to the petroleum-based polyethylene terephthalate. Furthermore, various primary alcohols were conveniently oxidized to their corresponding carboxylic acids in up to quantitative yields.

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Eco-friendly copper sulfate-catalyzed oxidation of amines to imines by hydrogen peroxide in water

Cited by 24 publications

References 49 publications

Metal-Free Oxidative Coupling of Benzylamines to Imines under an Oxygen Atmosphere Promoted Using Salicylic Acid Derivatives as Organocatalysts

Metal-Free Oxidative Coupling of Benzylamines to Imines under an Oxygen Atmosphere Promoted Using Salicylic Acid Derivatives as Organocatalysts

Green Oxidation of Amines to Imines Based on the Development of Novel Catalytic Systems Using Molecular Oxygen or Hydrogen Peroxide

Au/Ag/Cu-Mixed Catalysts for the Eco-Friendly Oxidation of 5-Hydroxymethylfurfural and Related Compounds to Carboxylic Acids under Atmospheric Oxygen in Water

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