title: Formation of Tetrahydrofuran Derivatives and Acetonylation of Alkenes Using Carbon Radicals Derived from Manganese(III) Oxidation of Diketene.
abstract: Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed.
authors.affiliation: Department of Chemistry, Faculty of Science, and Department of Environmental Science, Graduate School of Natural Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto 860, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishino
authors.forename: Van-Ha
authors.initials: VH
authors.lastname: Nguyen
authors.forename: Shinji
authors.initials: S
authors.lastname: Yoshinaga
authors.forename: Kazu
authors.initials: K
authors.lastname: Kurosawa