1669-44-9Relevant articles and documents
Brown et al.
, p. 3503 (1970)
Mild Chemoenzymatic Oxidation of Allylic sec-Alcohols. Application to Biocatalytic Stereoselective Redox Isomerizations
Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
, p. 2413 - 2419 (2018/03/13)
The design of catalytic oxidative methodologies in aqueous medium under mild reaction conditions and using molecular oxygen as final electron acceptor represents a suitable alternative to the traditional oxidative transformations. These methods are especially relevant if other functionalities that can be oxidized are present within the same molecule, as in the case of allylic alcohols. Herein we apply a simple chemoenzymatic system composed of the laccase from Trametes versicolor and 2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO) to oxidize a series of racemic allylic sec-alcohols into the corresponding α,β-unsaturated ketones. Afterward, these compounds react with different commercially available ene-reductases to afford the corresponding saturated ketones. Remarkably, in the case of trisubstituted alkenes, the bioreduction reaction occurred with high stereoselectivity. Overall, a bienzymatic one-pot two-step sequential strategy has been described with respect to the synthesis of saturated ketones starting from racemic allylic alcohols, thus resembling the metal-catalyzed redox isomerizations of these derivatives that have been previously reported in the literature.
Cooperative Electrocatalytic and Chemoselective Alcohol Oxidation by Shvo's Catalyst
Lybaert, Jeroen,Trashin, Stanislav,Maes, Bert U. W.,De Wael, Karolien,Abbaspour Tehrani, Kourosch
supporting information, p. 919 - 925 (2017/03/27)
A new electrocatalytic conversion of alcohols to ketones and aldehydes was developed based on an electrochemical study of Shvo's complex. The oxidation of secondary alcohols was efficiently performed under mild conditions using a catalytic amount of Shvo's catalyst, in combination with a sub-stoichiometric amount of 2,6-dimethoxy-1,4-benzoquinone in N,N-dimethylformamide at 80 °C. The hydroquinone thus formed is continuously reoxidized with the aid of an electrochemical device. Excellent yields for different ketones, aromatic as well as aliphatic and α,β-unsaturated ketones, are obtained. In addition, chemoselectivity towards oxidation of the secondary alcohol is achieved when converting vicinal diols such as 1,2-octanediol and 1,2-decanediol. (Figure presented.).
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.
