title: Diphenylparabanic acid as a synthon for the synthesis of α-diketones and α-ketocarboxylic acids.
abstract: Diphenylparabanic acid was found to react with >2 equiv of organolithiums at -78 °C to effectively give the corresponding symmetrical α-diketones. However, upon treatment with 1 equiv of organolithium, the parabanic acid gave mainly 5-substituted 5-hydroxyimidazolidine-2,4-diones. On the other hand, Grignard reagents were less reactive toward the parabanic acid at low temperature, and selectively gave the corresponding 5-hydroxyimidazolidine-2,4-diones even if more than 1 equiv of the reagents was used. A tandem process in which the parabanic acid was first reacted with a Grignard reagent and then reacted in one-pot with an organolithium effectively gave the unsymmetrical α-diketone. 5-Substituted 5-hydroxyimidazolidine-2,4-diones were useful as versatile precursors for preparing α-ketocarboxylic acids as well as unsymmetrical α-diketones.
authors.affiliation: Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Watanabe
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Hamano
authors.forename: Shota
authors.initials: S
authors.lastname: Todaka
authors.forename: Takahiro
authors.initials: T
authors.lastname: Asaeda
authors.forename: Hisako K
authors.initials: HK
authors.lastname: Ijuin
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Matsumoto