Copper‐Catalyzed Aminoxylation of Different Types of Hydrocarbons with TEMPO: A Concise Route to <i>N‐</i>Alkoxyamine Derivatives

Li, Linyi; Yu, Zhibin; Shen, Zhitao

doi:10.1002/adsc.201500544

Cited by 18 publications

(10 citation statements)

References 67 publications

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“…With substrate 1 , competing alcohol oxidation increased as the catalyst loading decreased, but even using 20 mol % 5 * with 2 and 3 led to significant formation of byproducts resulting from substrate formylation and radical coupling with the TEMPO cocatalyst. Similar products have been observed for the CAN-catalyzed α-aminoxylation of ketones , and copper-catalyzed aminoxylation of ketones and hydrocarbons . Additionally, Hayton and co-workers proposed formation of an α-keto radical in a ketone (similar to compound 12 ), which is rapidly quenched by TEMPO following a one-electron concerted proton–electron transfer to produce the TEMPO-adduct …”

Section: Discussionsupporting

confidence: 59%

Aerobic Oxidation of 2-Phenoxyethanol Lignin Model Compounds Using Vanadium and Copper Catalysts

Díaz-Urrutia

Sedai

Leckett

et al. 2016

ACS Sustainable Chem. Eng.

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Lignin is the most abundant renewable aromatic-containing macromolecule in Nature. Intensive research efforts are underway to obtain additional value from lignin beyond current low-value heating. Aerobic oxidation has emerged as one promising alternative for the selective depolymerization of lignin, and a variety of models for the most abundant β-O-4 linkage have been employed. In this work, aerobic oxidation of the simple β-O-4 lignin models 2phenoxyethanol (2) and 1-phenyl-2-phenoxyethanol (3) were investigated using the oxovanadium complex (HQ) 2 V V (O)(O i Pr) (HQ = 8-oxyquinolinate) and CuCl/TEMPO/2,6-lutidine as catalysts in several different solvents at 100 °C (TEMPO = 2,2,6,6tetramethylpiperidine-1-oxyl). Using the vanadium catalyst, reactions proceed more readily in pyridine (vs dimethyl sulfoxide) presumably via an initial base-assisted alcohol dehydrogenation followed by oxidative C−C and C−O bond cleavage to afford phenol, formic acid and CO 2 . In contrast, the copper-catalyzed reactions suffer from extensive formylation of the substrate and radical coupling to give TEMPO-functionalized products. These results suggest that use of more complex β-O-4 lignin models is required for accurate comparison of selective oxidation catalysts.

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Section: Discussionsupporting

confidence: 59%

Aerobic Oxidation of 2-Phenoxyethanol Lignin Model Compounds Using Vanadium and Copper Catalysts

Díaz-Urrutia

Sedai

Leckett

et al. 2016

ACS Sustainable Chem. Eng.

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“…The sterically hindered N -alkoxy amines were synthesized in good to excellent yields by coupling TEMPO with hydrocarbyl radicals, which were generated in situ by t -BuOOH hydrogen abstraction from hydrocarbons . Most recently, a bpy(Cu)/TBHP catalytic system has been developed for synthesis of a broad range of N -alkoxyamine derivatives in excellent yields …”

Section: Tempo In Chemical Transformationmentioning

confidence: 99%

TEMPO in Chemical Transformations: From Homogeneous to Heterogeneous

et al. 2019

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The organic nitroxyl radical, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), finds a variety of industrial applications for chemical transformations. Because of economic and environmental concerns, the recovery and reuse of TEMPO with maintained high activity are of the utmost importance. In this Review, we summarize the most important advances made by the scientific community in TEMPO immobilization on various organic and inorganic support materials for recovery and reuse, and we discuss the activity and stability, as well as the procedures. Also summarized is the wide range of applications of TEMPO in both homogeneous and heterogeneous forms in chemical transformations, beginning from methodology tuning in synthetic chemistry to the use in polymer chemistry.

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“…The usefulness of the present catalysis was demonstrated by further elaboration of the product (Scheme ). , Direct esterification was achieved under conventional condensation conditions. Treatment of Zn dust provided the α-hydroxy ester 7 in 97% yield.…”

Section: Resultsmentioning

confidence: 99%

Chemoselective Catalytic α-Oxidation of Carboxylic Acids: Iron/Alkali Metal Cooperative Redox Active Catalysis

Tanaka

Yazaki

2020

J. Am. Chem. Soc.

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We developed a chemoselective catalytic activation of carboxylic acid for a 1e − radical process. α-Oxidation of a variety of carboxylic acids, which preferentially undergo undesired decarboxylation under radical conditions, proceeded efficiently under the optimized conditions. Chemoselective enolization of carboxylic acid was also achieved even in the presence of more acidic carbonyls. Extensive mechanistic studies revealed that the cooperative actions of iron species and alkali metal ions derived from 4 Å molecular sieves substantially facilitated the enolization. For the first time, catalytic enolization of unprotected carboxylic acid was achieved without external addition of stoichiometric amounts of Brønsted base. The formed redox-active heterobimetallic enediolate efficiently coupled with free radical TEMPO, providing synthetically useful α-hydroxy and keto acid derivatives.

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Copper‐Catalyzed Aminoxylation of Different Types of Hydrocarbons with TEMPO: A Concise Route to N‐Alkoxyamine Derivatives

Cited by 18 publications

References 67 publications

Aerobic Oxidation of 2-Phenoxyethanol Lignin Model Compounds Using Vanadium and Copper Catalysts

Aerobic Oxidation of 2-Phenoxyethanol Lignin Model Compounds Using Vanadium and Copper Catalysts

TEMPO in Chemical Transformations: From Homogeneous to Heterogeneous

Chemoselective Catalytic α-Oxidation of Carboxylic Acids: Iron/Alkali Metal Cooperative Redox Active Catalysis

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