Intramolecular Arene Hydroxylation versus Intermolecular Olefin Epoxidation by (μ-η²:η²-Peroxo)dicopper(II) Complex Supported by Dinucleating Ligand

Abstract

A discrete (mu-eta2:eta2-peroxo)Cu(II)2 complex, [Cu2(O2)(H-L)]2+, is capable of performing not only intramolecular hydroxylation of a m-xylyl linker of a dinucleating ligand but also intermolecular epoxidation of styrene via electrophilic reaction to the C=C bond and hydroxylation of THF by H-atom abstraction.

Modeling tyrosinase activity. Effect of ligand topology on aromatic ring hydroxylation: An overview

“…While copper(I) complex of ligand 2 failed to react with O 2 it is worth noting that the reaction of the dicopper(I) complex of the ligand 3 with O 2 in acetone at À80°C gave a dark-green (l-g 2 :g 2 -peroxo)dicopper(II) species, which eventually decomposes giving the hydroxylation of the mxylyl linker of the ligand [84]. This result can be explained by taking account of the decreased electron-donor ability of the pyridine of ligand 3 due to steric repulsion between the bound metal ion and the 6-methyl substituent.…”

“…Notably, the reactivity of (l-g 2 :g 2 -peroxo)dicopper(II) complex of a m-xylyl-based ligand 3 was investigated towards exogenous substrates [84]. These authors observed intermolecular epoxidation of styrene (O-atom transfer reaction) and hydroxylation of THF (Fig.…”

Synthesis and reactivity of (μ-η2:η2-peroxo)dicopper(II) complexes with dinucleating ligands: Hydroxylation of xylyl linker with a NIH shift

“…The Cu n /O 2 -mediated arene hydroxylation is of current interest for understanding the reaction mechanisms of dioxygen activating copper proteins in biological systems such as tyrosinase and utilizing metal complexes as oxidation catalysts [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Karlin and co-workers have first demonstrated that the (l-g 2 :g 2 -peroxo)Cu(II) 2 complexes, [Cu 2 (O 2 )(X-XYL-R)] 2+ , are capable of performing hydroxylation of the xylyl linkers of the supporting ligands [3][4][5].…”

“…Itoh and co-workers have shown that the phenolate hydroxylation by a (l-g 2 :g 2 -peroxo)copper(II) complex well mimics that performed by tyrosinase [9,12]. Recently, we have also found that a (l-g 2 :g 2 -peroxo)Cu(II) 2 having a xylyl linker [Cu 2 (O 2 )(H-L-H)] 2+ (3-O 2 ) is capable of performing not only intramolecular hydroxylation of the xylyl linker of the dinucleating ligand H-L-H, but also intermolecular epoxidation of styrene and hydroxylation of THF by hydrogen atom abstraction [13].…”

Kupferkatalysierte C‐C‐Kupplung von Thiolestern und Boronsäuren unter aeroben Bedingungen

“…Es -Disauerstoff-Chemie [20] schlagen die Autoren eine anfängliche aerobe Aktivierung des Cu I -koordinierten Thiolesters A zu einem höher oxidierten Cu zentrum und eine Aktivierung der Boronsäure durch Koordination der oxygenierten Spezies an das Borzentrum (C) lenken die nucleophile Gruppe R 2 zum Thiolester und erzeugen das gewünschte Keton 2 und das Cu II/III -Thiolat D. Abschließend reagiert D mit einem zweiten ¾quivalent Boronsäure, wodurch der schwach koordinierende Thioether 3 erzeugt wird, nach dessen Abspaltung die entscheidende oxygenierte Cu I -Spezies wieder in den Katalysezyklus eintreten kann. [21] Das von Liebeskind und Mitarbeitern beschriebene Katalysesystem für die aerobe Kreuzkupplung ist für Synthesechemiker aus verschiedenen Gründen interessant.…”