1192-78-5Relevant articles and documents
OXIDATION OF ALCOHOLS WITH OXOPEROXOBIS-(N-PHENYLBENZOHYDROXAMATO)MOLYBDENUM(VI)
Tomioka, Hiroki,Takai, Kazuhiko,Oshima, Koichiro,Nozaki, Hitosi,Toriumi, Koshiro
, p. 4843 - 4846 (1980)
The title complex oxidizes primary and secondary alcohols to the corresponding carbonyl compounds.Stereoselective epoxidation of allylic alcohols is also described.
Regio-, diastereo-, and chemoselectivities in the dioxirane oxidation of acyclic and cyclic allylic alcohols by methyl(trifluoromethyl)dioxirane (TFD): A comparison with dimethyldioxirane
Adam, Waldemar,Paredes, Rodrigo,Smerz, Alexander K.,Veloza, L. Angela
, p. 349 - 354 (1998)
The solvent-dependent shift in the regioselectivity of the geraniol epoxidation by methyl(trifluoromethyl)dioxirane (TFD) reveals that as for the less reactive dimethyldioxirane (DMD). hydrogen bonding stabilizes the transition state of the epoxidation. In protic media, the hydrogen bonding is exerted intermolecularly by the solvent, whereas in unpolar, non-hydrogen-bonding solvents intramolecular assistance through the adjacent hydroxy functionality comes into the play and the attack on the allylic alcohol moiety is favored. For chiral allylic alcohols, additional steric interactions control the π-facial selectivity in the conformationally fixed transition state. Analogous to DMD, the preferred dihedral angle in the hydrogen-bonded transition state of the TFD epoxidation constitutes approximately 130°, but contrary to DMD and for synthetic purposes important, the allylic alcohols and derivatives 1 and 3-5 investigated here are chemoselectively epoxidized by TFD without formation of the corresponding enones.
Hydroxyselenation of Allylic Alcohols
Cooper, Matthew A.,Ward, A. David
, p. 2327 - 2330 (1995)
Hydroxyselenation of terminal or cyclic allylic alcohols occurs with high regio- and stereoselectivity to give β,β'-dihydroxyphenylselenated adducts in high yields.A mechanism for this selectivity is proposed.The utility of these adducts is illustrated by the conversion of the hydroxyselenide (9a) to the epoxide (11) via the intermediacy of a selenone.
A SUPPORTED EPOXIDATION CATALYST FOR NUCLEOPHILIC OLEFINS
Okamoto, Yasushi,Still, W. Clark
, p. 971 - 974 (1988)
A polystyrene-supported peptid-linked epoxidation catalyst is described and its utility for the discovery of new epoxidants is discussed.
An investigation into oxo analogues of molybdenum olefin metathesis complexes as epoxidation catalysts for alkenes
Anderson, James C.,Smith, Neil M.,Robertson, Michelle,Scott, Mark S.
, p. 5344 - 5346 (2009)
The oxo-imido molybdenum complex 2a is an effective catalyst at low catalyst loadings (0.5 mol % or below) for the epoxidation of a range of alkenes with tBuOOH in PhMe at 90 °C. Reactions are complete in less than 4 h and the products are isolated in high yields. The catalytic system is chemoselective for the epoxidation of electron-rich alkenes and allylic alcohols.
Catalytic efficacy of an oxido-peroxido tungsten(VI) complex: Synthesis, X-ray structure and oxidation of sulfides and olefins
Amini, Mojtaba,Bagherzadeh, Mojtaba,Eftekhari-Sis, Bagher,Ellern, Arkady,Woo, L. Keith
, p. 1897 - 1905 (2013)
An oxido-peroxido tungsten(VI) complex [WO(O2)L(CH 30H)] using salicylidene benzoyl hydrazine as a tridentate ONO donor Schiff base (H2L) has been synthesized and characterized by elemental analysis, IR, 1H NMR, molar conductance data, and single-crystal X-ray analysis. The complex was used as a catalyst for epoxidation of olefins and oxidation of sulfides. The results show that epoxides and sulfoxides were produced in high yield, turnover number, and selectivity.
Diastereoselective epoxidation of cyclohexene derivatives by dioxiranes generated in situ. Importance of steric and field effects
Yang, Dan,Jiao, Guan-Sheng,Yip, Yiu-Chung,Wong, Man-Kin
, p. 1635 - 1639 (1999)
In this paper, diastereoselective epoxidation of substituted cyclohexenes (substrates 1-7) by dioxiranes generated in situ from ketones and Oxone was systematically investigated. The results revealed that the diastereoselectivity was determined by the steric and field effects of both dioxiranes and substrates, and high diastereoselectivity can be achieved by tuning the ketone structure. Among the ketones tested, 12 and 19 gave the best diastereoselectivities.
Stereoselective Synthesis of cis,cis-Configured Perhydroquinoxaline-5-Carbonitrile from Cyclohex-2-en-1-ol
Schulte, Adrian,Saito, Susumu,Wünsch, Bernhard
, p. 533 - 536 (2016)
cis,cis-Configured perhydroquinoxaline-5-carbonitrile 10 was synthesized stereoselectively by ditosylation of trans,cis-2,3-dihydroxycyclohexane-1-carbonitrile 4 and subsequent reaction with ethylenediamine. The diol precursor 4 was stereoselectively obtained by regioselective opening of the epoxide 3 with KCN in water avoiding hazardous Et2AlCN.
Kinetic resolution of epoxy alcohols with the Sharpless Ti-isopropoxide/tartaric ester complex
Maljutenko, Karolin,Paju, Anne,J?rving, Ivar,Pehk, T?nis,Lopp, Margus
, p. 608 - 613 (2016)
When investigating the Sharpless epoxidation of enol-protected 4-hydroxy-1,2-cyclopentanediones, the ability of the asymmetric Ti(OiPr)4/tartaric ester complex to discriminate between enantiomeric epoxides formed in situ was discovered, leading to the epoxide opening reaction of only one enantiomer. This observation was used in the kinetic resolution of racemic substituted 2,3-epoxy-4-hydroxy-cyclopentanol, to afford enantiomerically enriched epoxyalcohols in good yields and with ees up to 96%.
Olefin Epoxidation with α-Hydroperoxides of Esters, Amides, Ketones, and Nitriles
Rebek, Julius,McCready, Russell,Wolak, Raymond
, p. 705 - 706 (1980)
A number of α-substituted hydroperoxides are capable of olefin epoxidation; unusual cis-trans selectivities are observed in reactions with olefins substituted with phenyl-groups.
Catalytic Epoxidation of Alkenes with Oxone
Denmark, Scott E.,Forbes, David C.,Hays, David S.,DePue, Jeffrey S.,Wilde, Richard G.
, p. 1391 - 1407 (1995)
A practical, general and efficient protocol for the catalytic epoxidation of alkenes has been developed.The in situ generation of reactive dioxiranes capable of epoxidizing a variety of alkenes under biphasic conditions has been accomplished using phase transfer catalysts bearing a carbonyl group.Optimal epoxidation conditions employ 10 mol percent of 1-dodecyl-1-methyl-4-oxopiperidinium triflate (8d(+)OTf(-)) in a CH2Cl2/pH 7.5-8.0 biphase using potassium monoperoxosulfate (Oxone) as the oxidant.Optimization of the conditions identified (1) slow addition rate, (2) pH 7.5-8.0, (3) N-dodecyl chain, and (4) the triflate salt as key experimental and structural variables.A selection of nine olefins was successfully oxidized to the corresponding epoxides in 83-96percent yield.
Catalytic Epoxidation of Olefins with t-Butyl Hydroperoxide in the Presence of Polymer-supported Vanadium(V) an Molybdenum(VI) Complexes
Yokoyama, Toshiro,Nishizawa, Masato,Kimura, Tetsuo,Suzuki, Toshishige M.
, p. 3271 - 3276 (1985)
Oxovanadium(V) and oxomolybdenum(VI) ions have been incorporated into cross-linked polystyrene resins functionalized with iminodiacetic acid or diethylenetriamine derivatives.The polymer complexes have been used as catalysts in the epoxidation of olefins with t-butyl hydroperoxide.Vanadium(V) complexes promote epoxidation of allylic alcohols in a highly regioselective manner, e.g., 2,3-epoxide has been preferentially obtained in 98percent selectivity from (E)-geraniol at 80 deg C.The catalytic activity of the vanadium(V) complexes is generally higher than that of the molybdenum(VI) complexes in the epoxidation of allylic alcohols whereas an opposed trend holds for the epoxidation of cyclohexene.Life time of catalysts have been examined by repeated use of the complexes in the epoxidation of (E)-geraniol at 80 degC in benzene.Approximately 15-25percent of vanadium has been leaked out of the polymer beads on five time recycles leading to the decrease in the yield of 2,3-epoxide from initial value of 98percent to 95-93percent.Neither appreciable loss of metal nor reduction of catalytic activity has been observed in the molybdenum complex systems over five runs.
Chemo- and stereoselective reduction of α,β-epoxyketones with diisopropoxytitanium(III) tetrahydroborate
Ravikumar,Chandrasekaran, Srinivasan
, p. 9137 - 9142 (1996)
Reduction of α,β-epoxyketones with diisopropoxytitanium(III) tetrahydroborate in dichloromethane under mild conditions (-78°→20°C) provides anti- (or erythro-) α,β-epoxy alcohols in high yields with high degree of chemo- and stereoselectivity.
Photocatalytic oxidation of cyclohexene on titanium(IV)oxide
Klisakova, Jana,Kluson, Petr,Cerveny, Libor
, p. 1985 - 1997 (2003)
Photocatalytic oxidation of cyclohexene was carried out over a series of titanium(IV) oxide catalysts. These species acting together with molecular oxygen significantly differed in their surface and structural properties. Attention was paid to elimination of the total decomposition of the alkene molecules to water and carbon dioxide and to favour formation of reaction intermediates, comprising epoxide units. Experiments were performed in liquid phase at atmospheric pressure, room temperature and under UV illumination. A quartz reactor was used and the reaction mixture was agitated by oxygen. Significant variations in the reaction selectivity were detected as a function of catalyst structural properties.
Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts
Zhou, Zhuohong,Dai, Guoyong,Ru, Shi,Yu, Han,Wei, Yongge
supporting information, p. 14201 - 14205 (2019/10/02)
Over the past two decades, there have been major developments in the transition iron-catalyzed selective oxidation of alkenes to epoxides; a common structure found in drug, isolated natural products, and fine chemicals. Many of these approaches have enabled highly efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefin epoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6], various aromatic and aliphatic alkenes were successfully transformed into the corresponding epoxides with excellent yields as well as chemo- and stereo-selectivity. This catalytic system possesses the advantages of being able to avoid the use of expensive, toxic, air/moisture sensitive and commercially unavailable organic ligands. The generality of this methodology is simple to operate and exhibits high catalytic activity as well as excellent stability, which gives it the potential to be used on an industrial scale, and maybe opens a way for the catalytic oxidation reaction via inorganic-ligand coordinated iron catalysis.
Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide
Ma, Wenbao,Chen, Chen,Kong, Kang,Dong, Qifeng,Li, Kun,Yuan, Mingming,Li, Difan,Hou, Zhenshan
, p. 7287 - 7296 (2017/05/31)
The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n]3[Ta(O)3(η-O2)], P4,4,4,n=quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2O2. The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4]3[Ta(O)3(η-O2)] of up to 285 h?1, and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
