420849-79-2Relevant articles and documents
Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid
Amarante, Tatiana R.,Antunes, Margarida M.,Valente, Anabela A.,Paz, Filipe A. Almeida,Pillinger, Martyn,Gon?alves, Isabel S.
, p. 9690 - 9703 (2015/11/03)
The tungsten oxide/2,2′-bipyridine hybrid material [WO3(2,2′-bpy)]·nH2O (n = 1-2) (1) has been prepared in near quantitative yield by the reaction of H2WO4, 2,2′-bpy, and H2O in the mole ratio of ca. 1:2:700 at 160°C for 98 h in a rotating Teflon-lined digestion bomb. The solid-state structure of 1 was solved and refined through Rietveld analysis of high-resolution synchrotron X-ray diffraction data collected for the microcrystalline powder. The material, crystallizing in the orthorhombic space group Iba2, is composed of a one-dimensional organic-inorganic hybrid polymer, ∞1[WO3(2,2′-bpy)], topologically identical to that found in the previously reported anhydrous phases [MO3(2,2′-bpy)] (M = Mo, W). While in the latter the N,N′-chelated 2,2′-bpy ligands of adjacent corner-shared {MO4N2} octahedra are positioned on the same side of the 1D chain, in 1 the 2,2′-bpy ligands alternate above and below the chain. The catalytic behavior of compound 1 for the epoxidation of cis-cyclooctene was compared with that for several other tungsten- or molybdenum-based (pre)catalysts, including the hybrid polymer [MoO3(2,2′-bpy)]. While the latter exhibits superior performance when tert-butyl hydroperoxide (TBHP) is used as the oxidant, compound 1 is superior when aqueous hydrogen peroxide is used, allowing near-quantitative conversion of the olefin to the epoxide. With H2O2, compounds 1 and [MoO3(2,2′-bpy)] act as sources of soluble active species, namely, the oxodiperoxo complex [MO(O2)2(2,2′-bpy)], which is formed in situ. Compounds 1 and [WO(O2)2(2,2′-bpy)] (2) were further tested in the epoxidation of cyclododecene, trans-2-octene, 1-octene, (R)-limonene, and styrene. The structure of 2 was determined by single-crystal X-ray diffraction and found to be isotypical with the molybdenum analogue.
First lipase catalysed resolution of epoxy enol esters
Gravil, Sébastien,Veschambre, Henri,Chênevert, Robert,Bolte, Jean
, p. 6153 - 6157 (2007/10/03)
We report the first enzyme-catalysed kinetic resolution of epoxy enol esters. The lipase-promoted hydrolysis of these compounds provided α-hydroxyketones or α-hydroxyaldehydes (arising from the spontaneous rearrangement of the epoxy enols) and the residual esters with moderate to good enantioselectivity (E up to 100).
Epoxidation of electron-deficient αβ-unsatured carbonyl compounds over Keggin heteropoly compounds with acqueous H2O 2
Gao, Qiang,Ding, Yong,Liu, Haitao,Suo, Jishuan
, p. 716 - 718 (2007/10/03)
The epoxidation of a variety of electron-deficient α,β- unsaturated carbonyl compounds has been studied using a series of heteropoly compounds and aqueous hydrogen peroxide in acetonitrile. Among the heteropoly compounds investigated, (CTP)3VMo12O40 showed the highest catalytic performance for the epoxidation of these compounds.
Catalytic asymmetric epoxidation of aliphatic enones using tartrate-derived magnesium alkoxides
Jacques,Richards,Jackson
, p. 2712 - 2713 (2007/10/03)
Simple aliphatic enones can be converted into the corresponding epoxides in 71-93% ee using tert-butylhydroperoxide in the presence of a catalyst derived from dibutylmagnesium and di-tert-butyl tartrate.
Aerobic epoxidation of alkenes catalysed by cobalt(II) 1,1,1,5,5,5-hexafluoroacetylacetonate or cobalt(II) benzoylacetonate
Hunter,Turner,Rimmer
, p. 4461 - 4466 (2007/10/03)
The aerobic epoxidation of terminal or electron deficient alkenes with an aldehyde does not proceed with cobalt(II) acetylacetonate but goes to completion with the cobalt(II) benzoylacetonate and cobalt(II) 1,1,1,5,5,5-hexafluoroacetylacetonate complexes.
A Novel Oxidation of Internal Alkynes with Hydrogen Peroxide Catalyzed by Peroxotungsten Compounds
Ishii, Yasutaka,Sakata, Yasuyuki
, p. 5545 - 5547 (2007/10/02)
Internal alkynes underwent a novel oxidation with aqueous hydrogen peroxide catalyzed by peroxotungsten compounds under two-phase conditions using chloroform as the solvent, giving α,β-epoxy ketones and α,β-unsaturated ketones as principal products.The epoxidation of α,β-unsaturated ketones by this catalyst-oxidant system appeared to involve the electrophilic attack of the peroxo species to the double bond.
A NOVEL REACTION OF α-HALOEPOXIDES WITH TRIALKYLSTANNATES
Corey, L. D.,Singh, S. M.,Oehlschlager, A. C.
, p. 1821 - 1827 (2007/10/02)
The reaction of α-haloepoxides with zinc powder or reagents containing tialkylstannate anion yields allylic alcohols by anti elimination of carbon halogen and adjacent carbon epoxy oxygen bonds.Appreciable Z -> E isomerization occurs in both types of reactions but the experimental results indicate that the conversion of erythro α-bromoepoxides to E allylic alcohols by zinc or trialkylstannates shows sufficient sterospecificity to be synthetically useful.
