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Biomimetic modeling of copper complexes: a study of enantioselective catalytic oxidation on d-(+)-catechin and L-( - )-epicatechin with copper complexes.

Mutti FG, Pievo R, Sgobba M, Gullotti M, Santagostini L - Bioinorg Chem Appl (2008)

Bottom Line: The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones.The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower.In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Chimica Inorganica, Metallorganica e Analitica "Lamberto Malatesta", Università di Milano, Istituto ISTM-CNR, Via Venezian 21, 20133 Milano, Italy.

ABSTRACT
The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( - )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

No MeSH data available.


Absolute stereochemistry configuration ofthe catechols.
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fig2: Absolute stereochemistry configuration ofthe catechols.

Mentions: Thecatalytic oxidations of catechols are the most widely employed test reaction to investigate thebehavior of tyrosinase and catechol oxidase model complexes. Previous studies[24–27] have shown that chiral dinuclear and trinuclear copper complexes wereable to display stereo-discriminating ability towards optically activecatechols to give the corresponding o-quinones.To confirm this behavior, new chiral catechols were employed in these catalyticstereoselective oxidations. D-(+)-catechin and L-(–)-epicatechin(flavan-3-ols) (Figure 2) constitute a class of phenolic compounds ubiquitousin plants and widely found in fruits, vegetables, and beverages [33–35]. Inparticular, they are one of the major quality factors in grapes and then in theresulting wine [36, 37].


Biomimetic modeling of copper complexes: a study of enantioselective catalytic oxidation on d-(+)-catechin and L-( - )-epicatechin with copper complexes.

Mutti FG, Pievo R, Sgobba M, Gullotti M, Santagostini L - Bioinorg Chem Appl (2008)

Absolute stereochemistry configuration ofthe catechols.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553160&req=5

fig2: Absolute stereochemistry configuration ofthe catechols.
Mentions: Thecatalytic oxidations of catechols are the most widely employed test reaction to investigate thebehavior of tyrosinase and catechol oxidase model complexes. Previous studies[24–27] have shown that chiral dinuclear and trinuclear copper complexes wereable to display stereo-discriminating ability towards optically activecatechols to give the corresponding o-quinones.To confirm this behavior, new chiral catechols were employed in these catalyticstereoselective oxidations. D-(+)-catechin and L-(–)-epicatechin(flavan-3-ols) (Figure 2) constitute a class of phenolic compounds ubiquitousin plants and widely found in fruits, vegetables, and beverages [33–35]. Inparticular, they are one of the major quality factors in grapes and then in theresulting wine [36, 37].

Bottom Line: The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones.The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower.In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Chimica Inorganica, Metallorganica e Analitica "Lamberto Malatesta", Università di Milano, Istituto ISTM-CNR, Via Venezian 21, 20133 Milano, Italy.

ABSTRACT
The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( - )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate.

No MeSH data available.