title: Synthesis of the Methyl Ester of Tritium-labeled AK-toxin I, a Host-specific Toxin Produced by Alternaria alternata Japanese Pear Pathotype.
abstract: AK-toxin I, a host-specific toxin to Japanese pear (Pyrus serotina), was synthesized as its methyl ester from three precursor fragments: conjugated diene-carboxylic acid, chiral epoxyalcohol and β-methylphenylalanine. The epoxyalcohol fragment was derived from D-fructose, in which effective homologation of the hemiacetal carbon to alkyne by using dimethyl 1-diazo-2-oxopropylphosphonate was the key reaction. The diene-carboxylic acid fragment was prepared by repeated Wittig reactions, and was combined with the epoxyalcohol fragment by the Stille reaction. Esterification of the combined product with the stereochemically-pure β-methylphenylalanine fragment afforded the target compound. This method was used to prepare the methyl ester of tritium-labeled AK-toxin I with a specific radioactivity of 213 GBq/mmol.
authors.affiliation: a Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University.
authors.forename: M
authors.initials: M
authors.lastname: Okada
authors.affiliation: a Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University.
authors.forename: H
authors.initials: H
authors.lastname: Miyagawa
authors.affiliation: a Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University.
authors.forename: T
authors.initials: T
authors.lastname: Ueno
keywords: AK-toxin; Japanese pear; homologation to alkyne; host-specific toxin; tritium-labeling