Copper‐Mediated Selective Oxidation of a CH Bond

Boldron, Christophe; Gámez, Patrick; Tooke, Duncan M.; Spek, Anthony L.; Reedijk, Jan

doi:10.1002/anie.200462946

Cited by 57 publications

(24 citation statements)

References 19 publications

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“…[49] Complexes 1-3 and 5: The two consecutive irreversible oxidation peaks observed with the Zn-pyramol complexes 2 and 3 (Table 2 and Figures 16 and 17) are assigned to the ligand dehydrogenation (pyramol to pyrimol), and to the phenoxyl radical formation and its consequent oxidation products, respectively (as observed for the free ligand Hpyramol). Similarly, the sole irreversible oxidation peak observed in the voltammograms of the Zn-pyrimol complexes 1 and 5 corresponds to the oxidation of the phenolic moiety to phenoxyl radicals, and the subsequent oxidation products.…”

Section: Full Papermentioning

confidence: 90%

Unique Ligand‐Based Oxidative DNA Cleavage by Zinc(II) Complexes of Hpyramol and Hpyrimol

Maheswari

Barends

Özalp-Yaman

et al. 2007

Chemistry A European J

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The zinc(II) complexes reported here have been synthesised from the ligand 4‐methyl‐2‐N‐(2‐pyridylmethyl)aminophenol (Hpyramol) with chloride or acetate counterions. All the five complexes have been structurally characterised, and the crystal structures reveal that the ligand Hpyramol gradually undergoes an oxidative dehydrogenation to form the ligand 4‐methyl‐2‐N‐(2‐pyridylmethylene)aminophenol (Hpyrimol), upon coordination to ZnII. All the five complexes cleave the ϕX174 phage DNA oxidatively and the complexes with fully dehydrogenated pyrimol ligands were found to be more efficient than the complexes with non‐dehydrogenated Hpyramol ligands. The DNA cleavage is suggested to be ligand‐based, whereas the pure ligands alone do not cleave DNA. The DNA cleavage is strongly suggested to be oxidative, possibly due to the involvement of a non‐diffusible phenoxyl radical mechanism. The enzymatic religation experiments and DNA cleavage in the presence of different radical scavengers further support the oxidative DNA cleavage by the zinc(II) complexes.

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Section: Full Papermentioning

confidence: 90%

Unique Ligand‐Based Oxidative DNA Cleavage by Zinc(II) Complexes of Hpyramol and Hpyrimol

Maheswari

Barends

Özalp-Yaman

et al. 2007

Chemistry A European J

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“…To ascertain the influencing factors, NaOMe was added to test the influence of the basic cocatalyst on the reaction because NaOMe is believed to have the power to remove protons from the phenol substrate and thus facilitate the oxidation of the phenol in homogeneous systems 14. Furthermore, Reedijk et al have reported that the NaOMe and phenol can bridge two copper atoms to form a mixed μ‐methoxido‐μ‐phenoxido‐bridged dinuclear copper species, namely neocuproine which is the key intermediate of the reaction 13a. As shown in Table 1, when NaOMe was added as the cocatalyst, the PPE selectivity decreases for both 1 and 2 and the conversion of DMP for 1 decreases.…”

Section: Resultsmentioning

confidence: 99%

Construction of Two Discrete Molecular High‐Nuclearity Copper(II) Complexes as Heterogeneous Catalysts for Oxidative Coupling Polymerisation of 2,6‐Dimethylphenol

Hou

Guo

et al. 2009

Eur J Inorg Chem

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Reaction of a rigid conjugated clamp‐like multi‐pyridineligand N,N′‐bis(pyridin‐3‐yl)‐2,6‐pyridinedicarboxamide (H2L) with CuSO4·5H2O or Cu(OAc)2 resulted in the formation of two high‐nuclearity, discrete molecular copper(II) complexes, namely [Cu10(H2L)5(SO4)8(μ3‐OH)4(H2O)2]·4CH3CH2OH·7H2O (1) and [Cu6(L)4(CH3COO)4]·2DMF·6H2O (2). In 1, ten copper atoms are engaged by five H2L ligands, eight SO42– and four μ3‐OH groups to form a novel decanuclear copper complex which sits on a crystallographic twofold axis passing through the centre of the complex. The structure of 2 features a hexanuclear copper cage and a crystallographic centre of inversion is at the mid‐point of the compound. The rigid conjugated clamp‐like H2L ligands, polydentate in nature, form a “coordination pocket” arising from their “arms” to entrap the copper atoms and play an important role in the assembly of discrete molecular high‐nuclearity complexes 1 and 2. Applications of 1 and 2 as heterogeneous catalysts for the oxidative polymerisation of 2,6‐dimethylphenol showed very promising results at ambient temperature and these novel catalytic systems are very mild, efficient, regioselective and easily recyclable. The interesting catalytic properties of 1 and 2 can be attributed to their particular structural characteristics and their unusual reactivities based on cooperativity or electron transfer between multicopper centres. Magnetic studies of these copper(II) cages indicate antiferromagnetic behaviour. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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“…Next, a survey of the activity of other copper salts revealed Cu(OAc) 2 to be the most effective catalyst for the esterification (Table 1, entries [5][6][7][8][9][10][11][12][13][14]. Copper(II) halides like CuCl 2 and CuBr 2 only provided trace amounts of the esterified product (Table 1, entries 5 and 6).…”

Section: Letter Syn Lettmentioning

confidence: 99%

Copper(II)-Catalyzed Oxidative Esterification of Substituted p-Cresols under Ligand- and Additive-Free Conditions

Zhang

Huang

Zhai

et al. 2015

Synlett

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Cu(OAc) 2 (10 mol%) ambient air MeCN, 75 °C + R 1 , R 2 = alkyl or alkoxy R 3 = aryl or alkyl 36-86% 17 examplesAbstract A facile, atom-economical, and efficient Cu(OAc) 2 -catalyzed oxidative esterification of substituted p-cresols was developed with ambient air as the terminal oxidant. This ligand-and additive-free esterification protocol allows an environmentally benign and reagent-economical access to benzyl esters.

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Copper‐Mediated Selective Oxidation of a CH Bond

Cited by 57 publications

References 19 publications

Unique Ligand‐Based Oxidative DNA Cleavage by Zinc(II) Complexes of Hpyramol and Hpyrimol

Unique Ligand‐Based Oxidative DNA Cleavage by Zinc(II) Complexes of Hpyramol and Hpyrimol

Construction of Two Discrete Molecular High‐Nuclearity Copper(II) Complexes as Heterogeneous Catalysts for Oxidative Coupling Polymerisation of 2,6‐Dimethylphenol

Copper(II)-Catalyzed Oxidative Esterification of Substituted p-Cresols under Ligand- and Additive-Free Conditions

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