Mechanism of Selective C–H Hydroxylation Mediated by Manganese Aminopyridine Enzyme Models

Ottenbacher, Roman V.; Talsi, Evgenii P.; Bryliakov, Konstantin P.

doi:10.1021/cs5013206

Cited by 81 publications

(85 citation statements)

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“…Counter to the earlier expectations [85], the possibility of esterification of the initially formed alcohol has been ruled out since separate experiments have shown that under …”

Section: Elucidation Of the Mechanism Of C-h Oxidations With H2o2 In mentioning

confidence: 99%

“…Bryliakov and co-workers synthesized complexes 22 and 23, bearing electron-donating substituents, that exhibited superior efficiencies (as compared with catalysts 15, 18, 19) in benzylic oxidations (Table 3, entries 6 and 7) [85]. Cumenes were oxidized preferentially into the corresponding alcohols, while ethylbenzene afforded mostly acetophenone.…”

Section: Initially Costas and Co-workers Reported That Complexes [(Mmentioning

confidence: 99%

“…To date, it is only the mechanism of catalytic C-H hydroxylation on Mn-aminopyridine catalysts that has been studied in more detail [85]; in particular, the analysis of kinetic isotope effect (kH/kD), isotopic labeling data, and linear free energy relationships has been reported. The crucial findings were the observation of (1) a primary kH/kD of 3.5-3.9 for the oxidation of cumene/α-2 H-cumene, indicating that the hydrogen atom lies on the reaction coordinate and participates in C-H bond breaking step; (2) linear Hammett correlation for the oxidation of a series of p-substituted cumenes, with the ρ + of −1.0, witnessing electrophilic active species, and electron-deficient transition state; (3) linear correlation between the C-H bond dissociation energies (BDEs) of the substrates and the logarithms of rates of their oxidations, reflecting a common oxidation mechanism; and (4) partial incorporation of 18 O from added 18 O-labeled water into the hydroxylated product, supporting the "water-assisted" [87,88] pathway for the formation of active, presumably oxomanganese(V), species [85].…”

Section: Elucidation Of the Mechanism Of C-h Oxidations With H2o2 In mentioning

confidence: 99%

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Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

2016

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Non-heme iron(II) complexes are widespread synthetic enzyme models, capable of conducting selective C-H oxidation with H 2 O 2 in the presence of carboxylic acid additives. In the last years, structurally similar manganese(II) complexes have been shown to catalyze C-H oxidation with similarly high selectivity, and with much higher efficiency. In this mini-review, recent catalytic and mechanistic data on the selective C-H oxygenations with H 2 O 2 in the presence of manganese complexes are overviewed. A distinctive feature of catalyst systems of the type Mn complex/H 2 O 2 /carboxylic is the existence of two alternative reaction pathways (as found for the oxidation of cumenes), one leading to the formation of alcohol, and the other to ester. The mechanisms of formation of the alcohol and the ester are briefly discussed.

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“…Counter to the earlier expectations [85], the possibility of esterification of the initially formed alcohol has been ruled out since separate experiments have shown that under …”

Section: Elucidation Of the Mechanism Of C-h Oxidations With H2o2 In mentioning

confidence: 99%

Section: Initially Costas and Co-workers Reported That Complexes [(Mmentioning

confidence: 99%

Section: Elucidation Of the Mechanism Of C-h Oxidations With H2o2 In mentioning

confidence: 99%

See 1 more Smart Citation

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

2016

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“…At the same time, periodic mesoporous organosilicas (PMO) which are another kind of mesoporous materials are studied extensively, and the PMO materials show high catalytic activity in BV oxidation reaction especially combined with metalloporphyrins. Metalloporphyrins have attracted considerable interest because of their various physicochemical properties [72][73][74][75] and their capability to catalyze a variety of oxidation reactions, such as alkene epoxidation and alkane hydroxylation with molecular oxygen [76]. Jeong et al [77] prepared ordered metal-tetrakis(carboxyphenyl)porphyrin (metal = Fe, Cu, Sn) bridged periodic mesoporous organosilicas (M-TCPP-PMO) with high surface areas of about 350-1087 m 2 g −1 and ordered pore channels (TEM images as shown in Fig.…”

Section: Sn-containing Mesoporous Materials Catalystsmentioning

confidence: 99%

Sn-based catalysts for Baeyer-Villiger oxidations by using hydrogen peroxide as oxidant

Cui

Shi

2016

Sci. China Mater.

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Baeyer-Villiger (BV) oxidation is one of the most important transformation reactions in synthetic organic chemistry. Catalytic versions of the BV oxidation are particularly attractive in practical applications, because the catalytic transformation substantially simplifies reaction process while minimizing reactant consumption as well as waste production. Further benefits are expected from replacing peracids, the traditionally used oxidant, by low cost and environmentally friendly hydrogen peroxide (H2O2). This review will first introduce very briefly the features of BV oxidation reactions, and the corresponding oxidants traditionally used. Afterwards, the emphasis will be placed on the specific Sn-based catalysts, their performance comparison for the BV oxidation reaction by using H2O2 as oxidant, and the catalytic mechanisms of most Sn-based catalysts reported so far, including homogeneous Sn-based catalysts (such as Sn-based fluorous biphase system catalysts), heterogeneous Sn-based catalysts (such as Sn-based zeolite catalysts, Sn-based mesoporous composites, Sn-incorporated clay catalysts, Sn-based metal oxide composites and polymer supported Sn catalysts). Finally, the Sn-based catalysts for BV oxidation are outlooked for their potentials and perspectives in enhancing the performance and then accelerating the practical applications of BV oxidations by using H2O2. The developing direction of the Sn-based catalytic BV reaction is also illustrated.

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“…1. The Fe and Mn complexes ISSN 2056-9890 Figure 1 Common examples of linear tetradentate aminopyridine ligands.bearing this type of ligand show good catalytic activity for olefin epoxidation (Lyakin et al, 2012;Mikhalyova et al, 2012), as well as aromatic (Makhlynets & Rybak-Akimova, 2010) and aliphatic (Ottenbacher et al, 2015) C-H activation. Related copper(II) complexes with aminopyridine ligands have also been synthesized and characterized (Singh et al, 2017;Kani et al, 2000;Liebov et al, 2011).…”

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confidence: 99%

{1,1′-Bis[(pyridin-2-yl)methyl]-2,2′-bipiperidyl}(perchlorato)copper(II) perchlorate

2017

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The title complex, [Cu II (ClO 4 )(mesoPYBP)](ClO 4 ) {PYBP = 1,1 0 -bis[(pyridin-2-yl)methyl]-2,2 0 -bipiperidyl, C 22 H 30 N 4 }, was prepared and found to crystallize with two crystallographically independent complex salt moieties. The metal atoms of the cations adopt a pseudo-square-pyramidal coordination geometry, where the tetradentate aminopyridine ligands (PYBP) are wrapped around the Cu atoms in the equatorial plane. The Cu-O bonds involving an O atom of the coordinating perchlorate anion are approximately perpendicular to the plane. The two remaining non-coordinating perchlorate anions are involved in several C-HÁ Á ÁO hydrogen bonds with the PYBP ligand and balance the total charge of the complex salt. The two crystallographically independent moieties are related to each other via a pseudo-translation along the a-axis direction. Exact translational symmetry is broken by (i) a difference in the conformation of one of the piperidine rings, featuring a chair conformation in one of the cations, and a sterically disfavored boat conformation in the other; and (ii) by modulation of the non-coordinating perchlorate anions. Chemical contextThe design and synthesis of a family of linear tetradentate aminopyridine ligands, featuring a diamine derivative backbone (e.g. 1,2-cyclohexyldiamine or 2,2 0 -dipyrrolidyl) and two picolyl arms attached to the amine nitrogen atoms, have frequently been discussed (Murphy & Stack, 2006;Yazerski et al., 2014). Common examples of linear tetradentate aminopyridine ligands are shown in Fig. 1. The Fe and Mn complexes ISSN 2056-9890 Figure 1 Common examples of linear tetradentate aminopyridine ligands.bearing this type of ligand show good catalytic activity for olefin epoxidation (Lyakin et al., 2012;Mikhalyova et al., 2012), as well as aromatic (Makhlynets & Rybak-Akimova, 2010) and aliphatic (Ottenbacher et al., 2015) C-H activation. Related copper(II) complexes with aminopyridine ligands have also been synthesized and characterized (Singh et al., 2017;Kani et al., 2000;Liebov et al., 2011). Potential applications of these complexes include fluorescent sensing of NO. The copper(II) ion in complexes with an appended fluorophore is readily reduced by nitric oxide with concomitant fluorescence enhancement (Kumar et al. 2013a,b). Structural commentaryThe title compound crystallizes with two crystallographically independent moieties, consisting of a [Cu II (ClO 4 )(meso-PYBP)] {PYBP = 1,1 0 -bis[(pyridin-2-yl)methyl]-2,2 0 -bipiperidyl} cation and another non-coordinating ClO 4Like some other Cu II aminopyridine complexes (Singh et al., 2017;Kani et al., 2000;Liebov et al., 2011), the cationic complex consists of a five-coordinate Cu ion in a distorted square-pyramidal geometry.The tetradentate mesoPYBP ligand surrounds the metal ion in the basal plane (Fig. 2). One of the two remaining octahedral sites is occupied by the oxygen atom of a coordinating perchlorate anion, while the other site remains vacant. Another perchlorate anion in the outer sphere balances the net charge and ...

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Mechanism of Selective C–H Hydroxylation Mediated by Manganese Aminopyridine Enzyme Models

Cited by 81 publications

References 84 publications

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

Sn-based catalysts for Baeyer-Villiger oxidations by using hydrogen peroxide as oxidant

{1,1′-Bis[(pyridin-2-yl)methyl]-2,2′-bipiperidyl}(perchlorato)copper(II) perchlorate

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