6124-56-7Relevant academic research and scientific papers
Scope and limitations of one-pot multistep reactions with heterogeneous catalysts: The case of alkene epoxidation coupled to epoxide ring-opening
Fraile, José M.,García, Nuria,Herrerías, Clara I.,Mayoral, José A.
experimental part, p. 15 - 20 (2012/07/03)
The combination of two reactions in one-pot multistep system requires the compatibility not only between the catalysts of both reactions, but also between all the reaction components and conditions. In the case of the coupling of alkene epoxidation and epoxide ring opening, it has been possible to synthesize cyanohydrin and azidohydrin derivatives through a simple process that involves a one-pot multistep process by using a mixture of two heterogeneous catalysts, a silica-grafted Ti catalyst and ytterbium chloride, whose efficiency depends on the reactivity of the starting alkene. In addition, in some cases the mixture of catalysts can be recovered and reused in several one-pot multistep cycles. However, this system is not possible with electron-deficient alkenes, as the basic catalyst required for epoxidation has shown to be incompatible with the ring-opening process.
Amino-acid-mediated epoxidation of α,β-unsaturated ketones by hydrogen peroxide in aqueous media
Kim, Juhyun,Jung, Suhyun,Park, Seongsoon,Park, Sojung
experimental part, p. 2866 - 2868 (2011/06/21)
Amino acids, such as arginine and lysine, can be used as an efficient catalyst in the epoxidation of α,β-unsaturated ketones with aqueous hydrogen peroxide. Up to >99% conversion was obtained in the reaction toward 11 α,β-unsaturated ketones.
Catalytic enantioselective peroxidation of α,β-unsaturated ketones
Lu, Xiaojie,Liu, Yan,Sun, Bingfeng,Cindric, Brittany,Deng, Li
supporting information; body text, p. 8134 - 8135 (2009/02/02)
Despite the potential of chiral peroxides as biologically interesting or even clinically important compounds, no catalytic enantioselective peroxidation has been reported. With a chiral catalyst not only to induce enantioselectivity but also to convert a well established epoxidation pathway into a peroxidation pathway, the first efficient catalytic peroxidation has been successfully developed. Employing readily available α,β-unsaturated ketones and hydroperoxides and an easily accessible cinchona alkaloid catalyst, this novel reaction will open new possibilities in the asymmetric synthesis of chiral peroxides. Under different conditions a highly enantioselective epoxidation with the same starting materials, reagents, and catalyst has was also established. Copyright
Highly efficient epoxidation of α,β-unsaturated ketones by hydrogen peroxide with a base hydrotalcite catalyst prepared from metal oxides
Honma, Takayuki,Nakajo, Michiko,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 6229 - 6232 (2007/10/03)
The base hydrotalcite, prepared from MgO and Al2O3, acted as a highly efficient catalyst for the epoxidation of α,β-unsaturated ketones using aqueous hydrogen peroxide as an oxidant. This heterogeneous epoxidation has the advantages of a high efficiency of H2O2 utilization without organic solvents, a simple workup procedure, and reusability of the hydrotalcite catalyst.
Epoxidation of α,β-Unsaturated Ketones Using Hydrogen Peroxide in the Presence of Basic Hydrotalcite Catalysts
Yamaguchi, Kazuya,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 6897 - 6903 (2007/10/03)
The basic layered hydrotalcites have been used as catalysts for the epoxidation of α,β-unsaturated ketones in heterogeneous reaction media using hydrogen peroxide as an oxidant. A wide variety of α,β-unsaturated ketones were oxidized to the corresponding epoxyketones in excellent yields under mild reaction conditions. For example, 2-cyclohexen-1-one gave 2,3-epoxycyclohexanone in 91% yield at 40°C for 5 h with high efficiency in hydrogen peroxide. The catalytic activity of the hydrotalcites increased as the basicity of their surfaces increased. In the case of the epoxidation of less reactive substrates, adding a cationic surfactant such as n-dodecyltrimethylammonium bromide (DTMAB) to the above oxidation system accelerated the epoxidation reaction. These hydrotalcite catalysts were easily separated from the reaction mixture and were reusable.
Kinetics and mechanism of the epoxidation of alkyl-substituted alkenes by hydrogen peroxide, catalyzed by methylrhenium trioxide
Al-Ajlouni, Ahmad M.,Espenson, James H.
, p. 3969 - 3976 (2007/10/03)
Epoxidations of alkyl-substituted alkenes, with hydrogen peroxide as the oxygen source, are catalyzed by CH3ReO3 (MTO). The kinetics of 28 such reactions were studied in 1:1 CH3CN-H2O at pH 1 and in methanol. To accommodate the different requirements of these reactions, 1H-NMR, spectrophotometric, and thermometric techniques were used to acquire kinetic data. High concentrations of hydrogen peroxide were used, so that diperoxorhenium complex CH3Re(O)(η2-O2)2(H 2O), B, was the only predominant and reactive form of the catalyst. The reactions between B and the alkenes are about 1 order of magnitude more rapid in the semiaqueous solvent than in methanol. The various trends in reactivity are medium-independent. The rate constants for B with the aliphatic alkenes correlate closely with the number of alkyl groups on the olefinic carbons. The reactions become markedly slower when electron-attracting groups, such as halo, hydroxy, cyano, and carbonyl, are present. The rate constants for catalytic epoxidations with B and those reported for the stoichiometric reactions of dimethyldioxirane show very similar trends in reactivity. These findings suggest a concerted mechanism in which the electron-rich double bond of the alkene attacks a peroxidic oxygen of B. These data, combined with those reported for the epoxidation of styrene (a term intended to include related molecules with ring and/or aliphatic substituents) by B and by the monoperoxo derivative of MTO, suggest that all of the rhenium-catalyzed epoxidations occur by a common mechanism. The geometry of the system at the transition state can be inferred from these data, which suggest a spiro arrangement.
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.
