1792-81-0Relevant articles and documents
A heterogeneous cis-dihydroxylation catalyst with stable, site-isolated osmium-diolate reaction centers
Severeyns, An,De Vos, Dirk E.,Fiermans, Lucien,Verpoort, Francis,Grobet, Piet J.,Jacobs, Pierre A.
, p. 586 - 589 (2001)
Involatile OsO4! A tetrasubstituted olefin is immobilized on SiO2 and reacts with OsO4 to form a stable osmate (IV) ester (see scheme), which is a leak-proof heterogeneous catalyst for the cis-dihydroxylation of olefins.
Idesia polycarpa (Salicaceae) leaf constituents and their toxic effect on Cerura vinula and Lymantria dispar (Lepidoptera) larvae
Feistel, Felix,Paetz, Christian,Lorenz, Sybille,Beran, Franziska,Kunert, Grit,Schneider, Bernd
, p. 170 - 179 (2017)
Phytochemical investigation of Idesia polycarpa (Salicaceae) resulted in the structure elucidation of nine previously undescribed phenolic natural products along with six known compounds. The compounds are structurally related to salicinoids that are known defense compounds from Salix and Populus species. The I. polycarpa diet was toxic, as shown in feeding experiments with larvae of Lymantria dispar, an herbivorous broadleaf tree generalist insect, and with larvae of Cerura vinula, a specialist adapted to poplar. The survival rate and mass gain of larvae was significantly lower when they fed on I. polycarpa leaves, compared to larvae fed on Populus nigra leaves. Potential reasons for the poor performance of both herbivores on I. polycarpa leaves are discussed.
Ionic liquid-immobilized catalytic system for biomimetic dihydroxylation of olefins
Closson, Adam,Johansson, Mikael,Baeckvall, Jan-E.
, p. 1494 - 1495 (2004)
A biomimetic catalytic system for dihydroxylation of olefins consisting of OsO4, N-methylmorpholine, and a flavin has been immobilized in an ionic liquid. This immobilized catalytic system is highly efficient for dihydroxylation with 30% aqueous H2O2 and it can be reused (at least 5 times) without loss of activity.
Osmium(III) and osmium(V) complexes bearing a macrocyclic ligand: A simple and efficient catalytic system for cis-dihydroxylation of alkenes with hydrogen peroxide
Sugimoto, Hideki,Ashikari, Kenji,Itoh, Shinobu
, p. 2154 - 2160 (2013)
A simple protocol that uses [OsIII(OH)(H2O)(L-N 4Me2)](PF6)2 (1; L-N 4Me2=N,N′-dimethyl-2,11-diaza[3.3](2,6) pyridinophane) as a catalyst and H2O2 as a terminal oxidant for efficient cis-1,2-dihydroxylation of alkenes is presented. Unfunctionalized (or aliphatic) alkenes and alkenes/styrenes containing electron-withdrawing groups are selectively oxidized to the corresponding vicinal diols in good to excellent yields (46-99 %). In the catalytic reactions, the stoichiometry of alkene:H2O2 is 1:1, and thus the oxidant efficiency is very high. For the dihydroxylation of cyclohexene, the catalytic amount of 1 can be reduced to 0.01 mol % to achieve a very high turnover number of 5500. The active oxidant is identified as the Os V(O)(OH) species (2), which is formed via the hydroperoxide adduct, an OsIII(OOH) species. The active oxidant 2 is successfully isolated and crystallographically characterized. The wizard of Os: A simple protocol that uses [OsIII(OH)(H2O)(L-N4Me 2)](PF6)2 (1) and H2O2 for efficient cis-1,2-dihydroxylation of alkenes is presented. Unfunctionalized (or aliphatic) alkenes and alkenes/styrenes containing electron-withdrawing groups were converted into the corresponding vicinal diols in good to excellent yields. It has been confirmed that the OsV(O)(OH) species (2) is the active oxidant, which is formed via the hydroperoxide adduct A. Copyright
Kinetics of Osmium Tetraoxide Catalyzed Trimethylamine N-Oxide Oxidations of Cyclohexene and α-Pinene to Diols
Erdik, Ender,Matteson, Donald S.
, p. 2742 - 2748 (1989)
The kinetics of the osmium tetraoxide catalyzed oxidation of cyclohexene and of α-pinene with trimethylamine N-oxide in aqueous tert-butyl alcohol are first order in total osmium species, first order in trimethylamine N-oxide, and zero order in alkene but are strongly dependent on which alkene is used.Thus, the rate-determining step is attack of the trimethylamine N-oxide on the osmium(VI) ester, which is the major reservoir of osmium in the system.The reaction of cyclohexene is inhibited by pyridine with an inverse first-order dependence.Addition of α-pinene in slight excess of the osmium tetraoxide inhibits the oxidation of cyclohexene by more than 2 orders of magnitude, but additional α-pinene has no further effect.The oxidation of α-pinene is not inhibited by pyridine or cyclohexene.Oxidation of trans-stilbene in the presence of α-pinene results in slight (3percent) but mechanistically significant asymmetric induction.A side reaction in the dihydroxylation of α-pinene, overoxidation to α-hydroxy ketone, is suppressed by increasing the concentration of trimethylamine N-oxide.
Contribution of flavonoids and catechol to the reduction of ICAM-1 expression in endothelial cells by a standardised Willow bark extract
Freischmidt,Jürgenliemk,Kraus,Okpanyi,Müller,Kelber,Weiser,Heilmann
, p. 245 - 252 (2012)
Introduction: A quantified aqueous Willow bark extract (STW 33-I) was tested concerning its inhibitory activity on TNF-α induced ICAM-1 expression in human microvascular endothelial cells (HMEC-1) and further fractionated to isolate the active compounds.
EPR, 1H and 2H NMR, and reactivity studies of the iron-oxygen intermediates in bioinspired catalyst systems
Lyakin, Oleg Y.,Bryliakov, Konstantin P.,Talsi, Evgenii P.
, p. 5526 - 5538 (2011)
Complexes [(BPMEN)FeII(CH3CN)2](ClO 4)2 (1, BPMEN = N,N′-dimethyl-N,N′-bis(2- pyridylmethyl)-1,2-diaminoethane) and [(TPA)FeII(CH 3CN)2](ClO4)2 (2, TPA = tris(2-pyridylmethyl)amine) are among the best nonheme iron-based catalysts for bioinspired oxidation of hydrocarbons. Using EPR and 1H and 2H NMR spectroscopy, the iron-oxygen intermediates formed in the catalyst systems 1,2/H2O2; 1,2/H2O 2/CH3COOH; 1,2/CH3CO3H; 1,2/m-CPBA; 1,2/PhIO; 1,2/tBuOOH; and 1,2/tBuOOH/CH3COOH have been studied (m-CPBA is m-chloroperbenzoic acid). The following intermediates have been observed: [(L)FeIII(OOR)(S)]2+, [(L)FeIV=O(S)]2+ (L = BPMEN or TPA, R = H or tBu, S = CH3CN or H2O), and the iron-oxygen species 1c (L = BPMEN) and 2c (L = TPA). It has been shown that 1c and 2c directly react with cyclohexene to yield cyclohexene oxide, whereas [(L)Fe IV=O(S)]2+ react with cyclohexene to yield mainly products of allylic oxidation. [(L)FeIII(OOR)(S)]2+ are inert in this reaction. The analysis of EPR and reactivity data shows that only those catalyst systems which display EPR spectra of 1c and 2c are able to selectively epoxidize cyclohexene, thus bearing strong evidence in favor of the key role of 1c and 2c in selective epoxidation. 1c and 2c were tentatively assigned to the oxoiron(V) intermediates.
A New Regio- and Stereo-selective Functionalization of Allylic and Homoallylic Alcohols
Cardillo, Giuliana,Orena, Mario,Porzi, Gianni,Sandri, Sergio
, p. 465 - 466 (1981)
A new, highly regio- and stereo-selective synthesis of cyclic iodocarbonates of allylic and homoallylic alcohols involving cyclofunctionalization of the corresponding alcohol carbonates is described.
Structure and catalytic activity of a new iron(ii) complex with a tetradentate carboxamide ligand: The effect of the outer-sphere donor on the chemoselectivity of the metal complex catalyst
Shteinman
, p. 1328 - 1334 (2012)
The interaction between Fe(ClO4) or Fe(OTf)2(MeCN) 2 and 2 equiv of the potentially tetraden- tate ligand bis(2-pyridyl)methyl-2-pyridinecarboxamide (Py2CHNHCOPy, tpcaH) yields the iron(II) com- plex [FeII(tpcaH)2]X2 (X = ClO4, OTf), in which, according to X-ray crystallography data, tpcaH is facially coordinated to the iron atom as a tridentate ligand through the carbonyl group and two pyridyl donors of the bis(2-pyridyl)methylcarboxamide moiety and the third pyridyl group is uninvolved in coordination. The oxi- dation of saturated and unsaturated hydrocarbons with hydrogen peroxide involving this complex has been investigated. The presence of the uncoordinated nitrogen donor in the outer coordination sphere of the com- plex exerts a crucial effect on it catalytic properties. Pleiades Publishing, Ltd., 2012.
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
