1603-79-8Relevant academic research and scientific papers
Fe(II) complexes that mimic the active site structure of acetylacetone dioxygenase: O2 and NO reactivity
Park, Heaweon,Bittner, Michael M.,Baus, Jacob S.,Lindeman, Sergey V.,Fiedler, Adam T.
, p. 10279 - 10289 (2012)
Acetylacetone dioxygenase (Dke1) is a bacterial enzyme that catalyzes the dioxygen-dependent degradation of β-dicarbonyl compounds. The Dke1 active site contains a nonheme monoiron(II) center facially ligated by three histidine residues (the 3His triad); coordination of the substrate in a bidentate manner provides a five-coordinate site for O2 binding. Recently, we published the synthesis and characterization of a series of ferrous β-diketonato complexes that faithfully mimic the enzyme-substrate intermediate of Dke1 (Park, H.; Baus, J.S.; Lindeman, S.V.; Fiedler, A.T. Inorg. Chem. 2011, 50, 11978-11989). The 3His triad was modeled with three different facially coordinating N3 supporting ligands, and substituted β-diketonates (acacX) with varying steric and electronic properties were employed. Here, we describe the reactivity of our Dke1 models toward O2 and its surrogate nitric oxide (NO), and report the synthesis of three new Fe(II) complexes featuring the anions of dialkyl malonates. Exposure of [Fe( Me2Tp) (acacX)] complexes (where R2Tp = hydrotris(pyrazol-1-yl)borate with R-groups at the 3- and 5-positions of the pyrazole rings) to O2 at -70 °C in toluene results in irreversible formation of green chromophores (λmax ~750 nm) that decay at temperatures above -60 °C. Spectroscopic and computational analyses suggest that these intermediates contain a diiron(III) unit bridged by a trans μ-1,2-peroxo ligand. The green chromophore is not observed with analogous complexes featuring Ph2Tp and PhTIP ligands (where PhTIP = tris(2-phenylimidazoly-4-yl)phosphine), since the steric bulk of the phenyl substituents prevents formation of dinuclear species. While these complexes are largely inert toward O2, Ph2Tp-based complexes with dialkyl malonate anions exhibit dioxygenase activity and thus serve as functional Dke1 models. The Fe/acac X complexes all react readily with NO to yield highspin (S = 3/2) {FeNO}7 adducts that were characterized with crystallographic, spectroscopic, and computational methods. Collectively, the results presented here enhance our understanding of the chemical factors involved in the oxidation of aliphatic substrates by nonheme iron dioxygenases.
A trispyrazolylborato iron malonato complex as a functional model for the acetylacetone dioxygenase
Siewert, Inke,Limberg, Christian
, p. 7953 - 7956 (2008)
(Chemical Equation Presented) Position available: A pentacoordinate iron(II) complex that binds and activates dioxygen shows dioxygenase activity and cleaves diethyl phenylmalonate, in analogy to acetylacetone dioxygenase (see scheme). The mechanism for the model compound allows interesting hypotheses to be made about the enzyme function.
Green synthesis of zinc oxide particles with apple-derived compounds and their application as catalysts in the transesterification of methyl benzoates
Alegria, Elisabete C. B. A.,Alves, Marta M.,Fátima Montemor, M.,Pombeiro, Armando J. L.,Ribeiro, Ana P. C.,Saraiva, Marta S.,Soliman, Mohamed M. A.
, p. 6488 - 6494 (2020)
ZnO nanoparticles (ZnONPs) were successfully synthesized using bravo-de-esmolfe apple extract in aqueous medium at room temperature. ZnO microparticles, prepared with a pure apple phytochemical, quercetin (ZnOq), or without phytochemicals (ZnO) were studied for comparative purposes. The re-use of apple waste for highly efficient catalyst production, based on green synthetic routes, can be added to the concept of a circular economy. The synthesized ZnO particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2adsorption/desorption Brunauer-Emmett-Teller (BET) theory. The XRD patterns indicated the formation of a hexagonal wurtzite phase with high purity and SEM and TEM analyses revealed the morphology of the particles. The apple extract produced spherical ZnONPs composed of round lamina-like structures, similar to the micro sized lamina-like shape of ZnOq and dissimilar to the flower-like shape of ZnO. The green synthesized ZnO nanoparticles (ZnONPs) led to a high product yield ofca. 96% within 24 h of reaction time in the transesterification reaction of different carboxylic esters.
Copper-catalysed Oxidation of Hydroxy Compounds by tert-Butyl Hydroperoxide Under Phase-transfer Conditions
Feldberg, Liron,Sasson, Yoel
, p. 1807 - 1808 (1994)
In the presence of quaternary ammonium phase-transfer agents copper salts catalyse the selective oxidative dehydrogenation of alcohols and hydroxy acids by tert-butyl hydroperoxide in aqueous-organic two-phase systems.
A Facially Coordinating Tris-Benzimidazole Ligand for Nonheme Iron Enzyme Models
Gunasekera, Parami S.,Abhyankar, Preshit C.,MacMillan, Samantha N.,Lacy, David C.
, p. 654 - 657 (2021)
Herein, we report a new tripodal tris-benzimidazole ligand (Tbim) that structurally mimics the 3-His coordination environment of certain nonheme mononuclear iron oxygenases. The coordination chemistry of Tbim was explored with iron(II) revealing a diverse set of coordination modes. The aerobic oxidation of biomimetic model substrate diethyl-2-phenylmalonate was studied using the Tbim?Fe and Fe(OTf)2.
VO(OEt)Cl2-induced oxidative deamination
Hirao, Toshikazu,Ohshiro, Yoshiki
, p. 3917 - 3918 (1990)
VO(OEt)Cl2 oxidized 2-phenylglycine derivatives via oxidative deamination and/or decarboxylation giving ethyl benzoate and ethyl phenylglyoxylate.
O2 activation at a trispyrazolylborato nickel(II) malonato complex
Hoof,Sallmann,Herwig,Braun-Cula,Limberg
, p. 16792 - 16795 (2017)
To support mechanistic inferences made for an iron-based dioxygenase model, a nickel analogue, i.e. a TpNi-malonate (1) was prepared. 1 proved to represent a rare case of a nickel complex reacting with O2 in a controlled manner-mechanistically different from the iron case-and leads to hydroxylation of the malonate.
Metal-free oxidative esterification of acetophenones with alcohols: A facile one-pot approach to α-ketoesters
Guo, Shiyu,Dai, Zhongxue,Yang, Zhao,Zhu, Ning,Wan, Li,Li, Xin,Liu, Chengkou,Fang, Zheng,Guo, Kai
, p. 98422 - 98426 (2016)
A novel and efficient oxidative esterification method for the synthesis of α-ketoesters has been developed under mild and environmentally benign conditions, which is a facile one-pot approach to α-ketoesters from commercially available acetophenones with alcohols, especially under metal-free conditions, with broad substrate scope. A possible mechanism is proposed on the basis of a series of control experiments and DMSO18 isotopic labelling experiments.
A remarkable effect of quaternary ammonium bromide for the N- hydroxyphthalimide-catalyzed aerobic oxidation of hydrocarbons
Matsunaka, Katsuhisa,Iwahama, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
, p. 2165 - 2168 (1999)
A methodology for the aerobic oxidation of organic substrates in the absence of any metal catalyst has been established using combined catalytic system consisting of N-hydroxyphthalimide and quaternary ammonium bromide. Thus, various hydrocarbons were successfully oxidized under dioxygen atmosphere to the corresponding oxygenated compounds in good selectivities.
Chemo- And diastereoselective synthesis of pyrrolidines from aroylformates and δ-tosylamino enones via P(NMe2)3-mediated reductive amination/base-catalyzed michael addition cascade
Liu, Rongfang,Liu, Jialin,Cao, Jilei,Li, Ruifeng,Zhou, Rong,Qiao, Yan,Gao, Wen-Chao
, p. 6922 - 6926 (2020)
A novel P(NMe2)3-mediated tandem (1 + 4) annulation between aroylformates and δ-tosylamino enones has been developed that affords a facile synthesis of functionalized pyrrolidines in moderate to excellent yields with exclusive chemoselectivity and high diastereoselectivity. Mechanistic investigation reveals that the reaction proceeds through an unprecedented P(NMe2)3-mediated reductive amination/base-catalyzed Michael addition cascade. The reaction herein also represents the first study of the reactivity patterns of the Kukhtin-Ramirez adducts toward ambiphilic nucleophile-electrophiles.
