title: Selective Oxidation of Vinyl Ethers and Silyl Enol Ethers with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate.
abstract: The oxidation of vinyl and silyl enol ethers with aqueous hydrogen peroxide was first achieved by the use of peroxotungstophosphate (PCWP) as the catalyst. For example, the oxidation of 1-ethoxy-1-octene with a stoichiometric amount of 35% H(2)O(2) in the presence of PCWP (0.5 mol %) in a mixed solvent of methanol and dichloromethane at room temperature gave 1-ethoxy-1-methoxy-2-hydroxyoctane, a synthetic equivalent of 2-hydroxyoctanal, in 70% yield. The oxidation of acyclic silyl enol ethers such as 1-[(trimethylsilyl)oxy]-1-octene under these conditions gave 1-hydroxy-2-octanone in 72% yield, while the same oxidation in dichloromethane alone resulted in cleavage of the enol double bond to form heptanal in 71% yield. Cyclic silyl enol ethers were converted into the corresponding alpha-hydroxy ketones in 48-71% yields under similar reaction conditions.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering & High Technology Research Center, Kansai University, Suita, Osaka 564, Japan.
authors.forename: Hiroyo
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Masaya
authors.initials: M
authors.lastname: Tsuda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sakaguchi
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Ishii