title: Unique reactivity of alpha,beta-unsaturated carboxylic acid imidazolides: catalytic asymmetric synthesis of alpha,beta-epoxy esters and alpha,beta-epoxy carboxylic acid derivatives.
abstract: Catalytic asymmetric synthesis of alpha,beta-epoxy esters and alpha,beta-epoxy carboxylic acid derivatives is described. Catalytic asymmetric epoxidation of alpha,beta-unsaturated carboxylic acid imidazolides using La-BINOL-Ph(3)As=O complex gave the corresponding alpha,beta-epoxy peroxy tert-butyl esters, which were directly converted to the alpha,beta-epoxy methyl esters by adding methanol to the reaction. This catalytic system had broad generality for epoxidation of various substrates. With the use of 5-10 mol% of the catalyst, both beta-aryl and beta-alkyl-substituted-alpha,beta-epoxy methyl esters were obtained in up to 91% yield and in up to 93% enantiomeric excess. In addition, efficient transformations of alpha,beta-epoxy peroxy tert-butyl esters into the alpha,beta-epoxy amides, alpha,beta-epoxy aldehydes, and gamma,delta-epoxy beta-keto esters are also reported.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Nemoto
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Tosaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohshima
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Shibasaki