533-60-8Relevant academic research and scientific papers
Selective oxidation of 1,2-diols by electrochemical method using organotin compound and bromide ion as mediators
Maki, Toshihide,Fukae, Kazuhiro,Harasawa, Hitomi,Ohishi, Takahiro,Matsumura, Yoshihiro,Onomura, Osamu
, p. 651 - 654 (1998)
A new electrochemical method for a selective oxidation of 1,2-diols to keto alcohols was explored. The method used dibutyltin oxide and bromide ion as mediators, and the oxidation was found to proceed effectively at 0°C under neutral conditions. Under these reaction conditions, 1,2-cyclohexanediol was selectively oxidized even in the presence of primary and secondary alcohols.
Mechanistic aspects of the bismuth-catalysed oxidation of epoxides to α-diketones
Antoniotti, Sylvain,Dunach, Elisabet
, p. 3459 - 3464 (2004)
The mechanism of the direct oxidation of 1,2-disubstituted epoxides to α-diketones catalysed by BiIII derivatives was examined. The oxidation was carried out in DMSO under dioxygen. Experimental evidence for the various steps of the reaction was obtained from spectroscopic data, isolation of intermediate species, reactions with Bi0, reaction under dinitrogen rather than under dioxygen, measurement of the oxygen consumption, cyclic voltammetry, and oxidations performed in the presence of methyl phenyl sulfoxide. The direct epoxide-to-diketone oxidation involves two main reaction steps: a first DMSO-mediated oxidative ring-opening of the oxirane ring, and a second Bi-catalysed oxidation to the α-diketone by dioxygen. A catalytic cycle is proposed combining the different results. A new alternative preparation of Bi(OTf)3 by oxidative dissolution of Bi0 is also described. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
A zinc-dependent alcohol dehydrogenase (ADH) from Thauera aromatica, reducing cyclic α- And β-diketones
Loderer, Christoph,Morgenstern, Frances,Ansorge-Schumacher, Marion
, p. 1872 - 1880 (2015)
Zinc-dependent alcohol dehydrogenases (ADHs) are valuable biocatalysts for the synthesis of chiral hydroxy compounds such as α-hydroxy ketones and diols, both valuable precursors for the synthesis of various pharmaceuticals. However, while highly active on aliphatic or phenyl-substituted diketones, most well characterized ADHs show no significant activity on cyclic α- and β-diketones. Therefore, this study aimed at the detection of a novel ADH capable to reduce these special targets. It involved a rational screening of biochemical pathways for enzymes with structurally related natural substrates. The so detected 6-hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase (ThaADH) from Thauera aromatica was cloned, expressed in Escherichia coli and purified by affinity chromatography. The characterization revealed a substrate specificity with highest activities on cyclic α- and β-diketones including 1,2-cyclohexanedione and 1,3-cyclopentanedione. Structural reasons for this extraordinary substrate spectrum were investigated with a homology model created via Swiss Model server. Although the quality of the model may be improved, it suggests that a bulky aromatic residue, that plays a crucial role in the definition of the substrate binding pockets of most ADHs, is replaced by a glycine residue in ThaADH. We propose that this structural difference leads to the formation of one large binding pocket instead of two smaller ones and consequently to a preference for cyclic diketones over linear bulky substrates. Thus, we have achieved both provision of a novel biocatalyst with high potential in chiral synthesis, and a possible explanation for the measured differences to known ADHs. The described structural motif might be used for identification of further enzymes with a related substrate scope.
Citric acid mediated catalytic osmylation/oxidative cleavage of electron deficient olefins: A vinyl sulfone study
Bobinski, Thomas P.,Fuchs, Philip L.
, p. 4151 - 4154 (2015)
The first broad catalytic dihydroxylation of enantiopure cyclic vinyl sulfones followed by oxidative cleavage of the resulting acyloin provides linear termini-differentiated polyketide fragments. This mild vinyl sulfone cleavage provides an effective alternative to the current ozonolysis protocol.
Aerobic photooxidation in water by polyoxotungstates: The case of uracil
Bonchio, Marcella,Carraro, Mauro,Conte, Valeria,Scorrano, Gianfranco
, p. 4897 - 4903 (2005)
Uracil photooxygenation occurs in acidic water (pH = 1) at 25°C, under oxygen (1 atm), irradiating with γ > 300 nm in the presence of selected polyoxometalates (POM). A marked diversity of photocatalytic behavior is registered for different POMs in terms of oxidation rate and selectivity. H 3PW12O40 (PW12) appears to be the most reactive photocatalyst, by far superior to isostructural complexes, leading to a product distribution typical of OH. dominated oxidations, while Na4W10O32 (W10) and Na 12[WZn3(H2O)2(ZnW9O 34)2] (Zn5W19) exhibit a preferential reactivity towards uracil glycol. Kinetic studies and radical scavenger probes, performed on target intermediates and model diols, highlight a substantial difference in the mechanism of photocatalysis by the three complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
One-pot production of phenazine from lignin-derived catechol
He, Zhimin,Qi, Wei,Ren, Tianyu,Yan, Ning
supporting information, p. 1224 - 1230 (2022/02/17)
Upgrading lignin-derived monomeric products is crucial in bio-refineries to effectively utilize lignin. Herein, we report a simple strategy to convert catechol to phenazine, a useful N-heterocycle three-aromatic-ring compound, whose current synthetic procedure is complex via a petroleum-derived feedstock. The reaction uses catechol as the sole carbon source and aqueous ammonia as reaction media and a nitrogen source. Without additional solvents, phenazine was obtained in 67% yield in the form of high purity crystals (>97%) over a Pd/C catalyst after a one-pot-two-stage reaction. When cyclohexane was used as a co-solvent in the first step, a higher yield (81%) and purity (>99%) were achieved. Mechanistic investigations involving control experiments and an isotope labeling study reveal that hydrogenation, amination, coupling and dehydrogenation reactions are the key steps leading to phenazine formation. The conversion of other lignin-derived catechols highlights that the protocol is extendable to produce substituted phenazines.
Selective Isomerization via Transient Thermodynamic Control: Dynamic Epimerization of trans to cis Diols
Macmillan, David W. C.,Oswood, Christian J.
supporting information, p. 93 - 98 (2022/01/03)
Traditional approaches to stereoselective synthesis require high levels of enantio- and diastereocontrol in every step that forms a new stereocenter. Here, we report an alternative approach, in which the stereochemistry of organic substrates is selectivel
Structural elucidation, DFT calculations and catalytic activity of dioxomolybdenum(VI) complexes with N–N donor ligand: Role of halogen atom coordinated to the molybdenum centre
Roy, Malini,Biswal, Debanjana,Pramanik, Nikhil Ranjan,Drew, Michael G.B.,Paul, Suvendu,Kachhap, Payal,Haldar, Chanchal,Chakrabarti, Syamal
, (2021/03/22)
Two new isostructural mononuclear dioxomolybdenum(VI) complexes of the formula MoO2X2L [where, X = Cl (1), Br (2)] have been synthesized with a N–N donor 2-(3-methyl-5-phenyl pyrazol-1-yl) benzthiazole ligand (L). The reaction is carried out in open air and the MoVO3+ centre in the precursor molecule, MoOX3L undergoes spontaneous aerial oxidation, leading to the formation of molybdenum(VI) complexes 1 and 2. The complexes are characterized by a wide range of spectroscopic techniques (IR, UV–Vis and 1H NMR) and elemental analyses. Crystal structures of the ligand and complexes 1 and 2 have been determined by single crystal X-ray diffraction which reveal a distorted octahedral geometry around the molybdenum(VI) centre in both the complexes. The ligand and the complexes build up fascinating supramolecular assembly via several non-covalent interactions including hydrogen bonding, C–H···π and π···π interactions. Further, a detailed study of Hirshfeld surface analysis and fingerprint plots of complexes 1 and 2 are presented for understanding the intermolecular interactions involved in building self-assembled frameworks. Supportive DFT and TD-DFT calculations have also been carried out. Electrochemical properties of the complexes have been examined by cyclic voltammetry. Catalytic performance of the synthesized complexes has been evaluated for the oxidation of different olefins in the presence of hydrogen peroxide.
Activation of H2O2over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates
Abramov, Pavel A.,Carbó, Jorge J.,Chesalov, Yuriy A.,Eltsov, Ilia V.,Errington, R. John,Evtushok, Vasilii Yu.,Glazneva, Tatyana S.,Ivanchikova, Irina D.,Kholdeeva, Oxana A.,Maksimchuk, Nataliya V.,Maksimov, Gennadii M.,Poblet, Josep M.,Solé-Daura, Albert,Yanshole, Vadim V.,Zalomaeva, Olga V.
, p. 10589 - 10603 (2021/09/02)
Zr-monosubstituted Lindqvist-type polyoxometalates (Zr-POMs), (Bu4N)2[W5O18Zr(H2O)3] (1) and (Bu4N)6[{W5O18Zr(μ-OH)}2] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C?C bonds in unfunctionalized alkenes and α,β-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an 17O-enriched dimer, (Bu4N)6[{W5O18Zr(μ-OCH3)}2] (2′), and H2O2 was also analyzed by 17O NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(μ-?2:?2-O2){ZrW5O18}2]6- as well as monomeric Zr-hydroperoxo [W5O18Zr(?2-OOH)]3- and Zr-peroxo [HW5O18Zr(?2-O2)]3- species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C?C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding α-oxygen transfer to the substrate as the rate-determining step. The calculations also showed that protonation of Zr-POM significantly reduces the free-energy barrier of the key oxygen-transfer step because of the greater electrophilicity of the catalyst and that dimeric species hampers the approach of alkene substrates due to steric repulsions reducing its reactivity. The improved performance of the Zr(IV) catalyst relative to Ti(IV) and Nb(V) catalysts is respectively due to a flexible coordination environment and a low tendency to form energy deep-well and low-reactive Zr-peroxo intermediates.
POLITAG-Pd(0) catalyzed continuous flow hydrogenation of lignin-derived phenolic compounds using sodium formate as a safe H-source
Campana, Filippo,Ferlin, Francesco,Silvetti, Matteo,Trombettoni, Valeria,Vaccaro, Luigi,Valentini, Federica
, (2021/07/09)
Phenols are aromatic biobased compounds and as they are accessible from lignin depolymerization, they can be a useful platform chemicals to produce value-added products. Herein we report our recent investigations on the definition of an approach to the efficient continuous flow selective hydrogenation of phenols in water. Our protocol is based on the use of sodium formate as a clean and safe hydrogen source in combination with our newly defined heterogeneous POLITAG-Pd(0) catalytic system. POLITAG is a polymeric heterogeneous support decorated with pincer-type ionic ligands proven to be highly efficient for the stabilization of Pd(0) nanoparticles. The results obtained are remarkable in comparison with other protocols that employ sodium formate as H-source. Indeed, our investigation has been extended to a variety of differently substituted phenolic compounds that have been hydrogenated with excellent to good selectivity in continuous flow conditions. Durability of the catalyst has been also tested with a representative continuous processing of over 100 mmol that showed no loss in efficiency and minimal metal leaching.
