1020-31-1Relevant academic research and scientific papers
Selective inhibition of bovine plasma amine oxidase by homopropargylamine, a new inactivator motif
Qiao, Chunhua,Jeon, Heung-Bae,Sayre, Lawrence M.
, p. 8038 - 8045 (2004)
Propargylic and activated allylic amines are known to inactivate the quinone-dependent plasma amine oxidases, possibly through active-site modification by the α,β-unsaturated aldehyde turnover products. Although homopropargylamine (1-amino-3-butyne, 1) is a nonobvious candidate as a mechanism-based inhibitor, 1 was found to be an unusually potent time- and concentration-dependent irreversible inactivator of bovine plasma amine oxidase (BPAO), exhibiting a 30 min IC50 of 2.9 μM at 30 °C ([BPAO] = 1.2 μM). Preserved cofactor redox activity of the denatured inactivated enzyme indicates that inactivation by 1 involves either a cofactor modification that reverses upon enzyme denaturation or a modification of an active-site residue. Because inactivation by 1 may involve enzyme alkylation by the reactive 2,3-butadienal (3) tautomer of the 3-butynal turnover product of 1, aldehyde 3 was prepared and was found to inactivate BPAO, but only at high concentration. In addition, whereas inhibition by 3 was blunted by the presence of mercaptoethanol, no such protection was observed against 1. The amine whose turnover should lead directly to 3 was prepared (1-amino-2,3-butadiene, 4) and was found to be an even more potent inactivator of BPAO than 1, exhibiting a 5 min IC50 of 1.25 μM. Rat liver mitochondrial monoamine oxidase was also inactivated by 4, as expected, but only very weakly by 1. Potential mechanisms explaining the selective inhibition of BPAO by 1 are discussed.
Substituent effects on the benzene ring. Determination of the intramolecular interactions of substituents in tert-alkyl-substituted catechols from thermochemical measurements
Verevkin, Sergey P.,Schick, Christoph
, p. 946 - 952 (2000)
Chemical equilibria of reactions of transalkylation among tert-butylphenols and tert-butylcatechols in the liquid phase were investigated in the temperature range 373-483 K. The molar enthalpies of fusion ΔcrlH°m of the catechol, 4-tert-butylcatechol, and 3,5-di-tert-butylcatechol were measured by DSC. The standard (p° = 0.1 MPa) molar enthalpies of formation ΔfH°m (cr) at the temperature T = 298.15 K were measured by means of combustion calorimetry for 4-tert-butylcatechol and 3,5-di-tert-butylcatechol. The standard molar enthalpies of sublimation of these compounds, and also the enthalpy of vaporization of 3-tert-butylcatechol, were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The measured reaction enthalpies were utilized for reconciliation of calorimetrically derived standard molar enthalpies of formation of tert-butyl-substituted phenols and catechols, as a stringent test of thermodynamic consistency of results derived from the diverse techniques employed in this work. Resulting values of ΔfH°m(g) of tert-butylcatechols were obtained at the temperature T = 298.15 K and used to derive their strain enthalpies. The intramolecular interactions of the substituents were discussed in terms of deviations of ΔfH°m(g) from the group additivity rules. No peculiarities in the interaction energy among alkyl groups and the hydroxyl groups in the ortho-, para-, and meta-positions of alkylcatechols in comparison with those of alkyl-substituted phenols were detected. Thus, no new parameters are needed for the prediction of the ΔfH°m(g) values of alkylcatechols by using the group-additive procedure.
Tyrosinase and catecholase-like activities of a dinuclear Cu(II) complex
Chatterjee, Arnab,Yadav, Hare Ram,Choudhury, Angshuman Roy,Ali, Anzar,Singh, Yogesh,Ghosh, Rajarshi
, p. 140 - 146 (2018)
A dinuclear Cu(II) complex was synthesized and crystallographically characterized. The compound was found to have antiferromagnetic interaction in between the Cu(II) centres in the molecule. It had weak intermolecular ferromagnetic interaction. The compound was found to be tyrosinase and catecholase active. In case of tyrosinase activity, the diphenol formed was isolated using thin layer chromatography (TLC) and characterized through 1H NMR as well as mass spectrometry. The o-quinone derivative formed in this reaction was characterized using GC–MS. The latter activity was monitored spectrophotometrically and the product o-quinone derivative was isolated (in MeOH and MeCN) column chromatographically and characterized using melting point determination. These were followed by Michealis–Menten kinetics with turnover numbers 4.95 × 103 and 1.58 × 103 h?1 in MeOH and MeCN, respectively.
Three-way cooperativity in d8 metal complexes with ligands displaying chemical and redox non-innocence
Deibel, Naina,Hohloch, Stephan,Schweinfurth, David,Weisser, Fritz,Grupp, Anita,Sarkar, Biprajit
, p. 15178 - 15187 (2014)
Reversible proton- and electron-transfer steps are crucial for various chemical transformations. The electron-reservoir behavior of redox non-innocent ligands and the proton-reservoir behavior of chemically non-innocent ligands can be cooperatively utilized for substrate bond activation. Although site-decoupled proton- and electron-transfer steps are often found in enzymatic systems, generating model metal complexes with these properties remains challenging. To tackle this issue, we present herein complexes [(cod-H)M(μ-L2-)M(cod-H)] (M=PtII, [1] or PdII, [2], cod=1,5-cyclooctadiene, H2L=2,5-di-[2,6-(diisopropyl)anilino]-1,4-benzoquinone), in which cod acts as a proton reservoir, and L2- as an electron reservoir. Protonation of [2] leads to an unusual tetranuclear complex. However, [1] can be stepwise reversibly protonated with up to two protons on the cod-H ligands, and the protonated forms can be stepwise reversibly reduced with up to two electrons on the L2- ligand. The doubly protonated form of [1] is also shown to react with OMe- leading to an activation of the cod ligands. The site-decoupled proton and electron reservoir sources work in tandem in a three-way cooperative process that results in the transfer of two electrons and two protons to a substrate leading to its double reduction and protonation. These results will possibly provide new insights into developing catalysts for multiple proton- and electron-transfer reactions by using metal complexes of non-innocent ligands.
SEMI-HINDERED PHENOLS. 1. SYNTHESIS OF 3,5-DI-TERT-BUTYLSALICYLIC ALDEHYDE
Dokukina, M. A.,Vol'eva, V. B.,Belostotskaya, I. S.,Komissarova, N. L.,Karmilov, A. Yu.,Ershov, V. V.
, p. 1868 - 1870 (1992)
Some differences were observed in the solid- and liquid-phase benzylic oxidation of 2-(hydroxy- or dialkylamino)methyl-4,6-di-tert-butylphenols.Oxidation of these semi-hindered phenols with lead tetraacetate gave a new compound: 3,5-di-tert-butyl-ortho-benzoquinone diacylal.Keywords: semi-hindered phenols, synthesis, aldehyde, benzylic alcohol, oxidation, liquid phase, solid phase.
Bioinspired copper(I) complexes that exhibit monooxygenase and catechol dioxygenase activity
Arnold, Aline,Metzinger, Ramona,Limberg, Christian
, p. 1198 - 1207 (2015)
New tripodal ligand L2 featuring three different pyridyl/imidazolyl-based N-donor units at a bridgehead C atom, from which one of the imidazolyl units is separated by a phenylene linker, was synthesized and investigated with regards to copper(I) complexation. The resulting complex [(L2)Cu]OTf (2OTf), the known complex [(L1)Cu]OTf (1OTf; L1 differs from L2 in that it lacks the phenylene spacer) and [(L3)Cu]OTf (3OTf), prepared from a known chiral, tripodal, N-donor ligand featuring pyridyl, pyrazolyl, and imidazolyl donors, were tested as catalysts for the oxidation of sodium 2,4-di-tert-butylphenolate (NaDTBP) with O2. Indeed, they mediated NaDTBP oxidation to give mainly the corresponding catecholate and quinone (Q). None of the complexes 1OTf, 2OTf, and 3OTf is superior to the others, as yields were comparable and, if the presence of protons is guaranteed by concomitant addition of the phenol DTBP, the oxidation can also be performed catalytically. For all complexes stoichiometric oxidations under certain conditions (concentrated solutions, high NaDTBP content) were found to also generate products typical for metal-mediated intradiol cleavage of the catecholate with O2. As shown representatively for 1OTf this dioxygenation sets in at a later stage of the reaction. Initially a copper species responsible for the monooxygenation must form from 1OTf/NaDTBP/O2, and only thereafter is the copper species responsible for dioxygenation formed and consumes Q as substrate. Hence, under these circumstances complexes 1OTf-3OTf show both monooxygenase and catechol dioxygenase activity.
Reaction of 1,1-Bis(Diphenylphosphino)Methane with O-Quinones and Naphtho[2,1-B]Furan-1,2-Dione. Novel Synthesis of Bis(Diphenylphosphoryl) Derivatives and their Antimicrobial Activity
Boulos, Leila S.,Ewies, Ewies F.,Ibrahim, Nabila M.,Mohram, Maysa E.
, p. 1706 - 1717 (2014)
The reaction of 1,1-bis(diphenylphosphino)methane with substituted o-quinones afforded the novel 6-[bis(diphenylphosphoryl)methyl]-and 6-bis(diphenyl phosphoryl)methylidene derivatives. Moreover, 1,1-bis(diphenylphosphino)methane reacts with 3,4,5,6-tetrabromo-o-benzoquinone to give only the new 6-[bis(diphenylphosphoryl)methyl] derivative. Mechanisms accounting for the formation of the new products are discussed. The antimicrobial activity of some of the newly synthesized compounds was also examined.
ORTHO-HYDROXYLATION SELECTIVE DES PHENOLS : I - VERS UN MODELE CHIMIQUE SIMPLE DES TYROSINASES.
Capdevielle, Patrice,Maumy, Michel
, p. 1573 - 1576 (1982)
The oxidation of cuprous phenoxides by molecular oxygen gives rise to catechols and ortho-benzoquinones.Such a new reaction provides a mechanistic approach to tyrosinase catalyzed oxidation of phenols.
Etude comparative des reactions par transfert monoelectronique entre les germylamines primaires, secondaires et tertiaires et la 3,5-di-tert-butylorthoquinone
Riviere-Baudet, Monique,Morere, Alain,Khallaayoun, Abdelhay
, p. 43 - 49 (1993)
Several germylamines were treated with 3,5-di-t-butylorthoquinone (1).Competitive 1,2 and 1,4 additions resulted using the tertiary amine Et3GeNPh2.The thermally unstable 1,4 adduct gives 2,2-dialkyl-4,5-(6,8-di-t-butyl)benzo-2-germa-1,3-dioxolanne.The 1,2 adduct leads via intermolecular redistribution to bis(triethylgermyl)oxide ((Et3Ge)2O), and aminal with partial regeneration of the initial quinone.These reations seem to proceed solely via a mono-electron transfer mechanism; the aminyl radical Ph2N and the transitory o-semiquinonic germylated radical formed in the reaction have been characterized by ESR spectroscopy.The o-semiquinonic radical then gives O-germyl-3,5-di-t-butylcatechol by hydrogen abstraction.As ethylene and isobutene have been characterized, these hydrogen abstractions occur from ethyl groups linked to germanium and from t-butyl groups belonging to the organic moieties.In the reaction of the secondary amine Et3GeN(H)Ph, a germylaminyl radical is mainly formed instead of an o-semiquinonic germylated radical, which can explain the lesser amount of germadioxolanne obtained.The quinone 1 is partially transformed in o-diphenol under the action of Mes3GeNH2.No germylated adducts are observed.Aminyl radicals characterized in several reactions between germylamines and 1 were also obtained via monoelectronic transfer between lithium amids and tri-t-butylnitrozobenzene (BNB), thus providing a new, useful method for obtaining such species.
Solid-Phase ortho-Hydroxylation of 2,4-Di-tert-butylphenol and Its Derivatives
Kurkovskaya, L. N.,Ovsyannikova, M. N.,Vol’eva, V. B.,Zhorin, V. A.
, p. 350 - 352 (2020)
Abstract: Direct phenol–catechol conversion has been realized as a result of the solid-phase reaction of 2,4-di-tert-butylphenol with cuprous oxide under high pressure and shear deformation on the Bridgman anvils. The yield of 3,5-di-tert-butylcatechol in this reaction was about 85%. When cupric oxide was used in the solid-phase process, oxidative coupling of the starting phenol took place, resulting in quantitative formation of tetra-tert-butyl-ortho-bisphenol. The reaction of 6-substituted derivatives of 2,4-di-tert-butylphenol with cuprous oxide was used as an example to demonstrate the possibility of substitutive ortho-hydroxylation yielding 7–20% of pyrocatechols.
