74(P-67) ニトロンの1,3-双極子付加反応によるキラルアレンのNMRを用いた絶対配置決定(ポスター発表の部)

概要

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As a series of our studies on NMR methods for determining the absolute configuration of chiral secondary alcohols, carboxylic acids, and sulfoxides by combining them with various types of chiral anisotropic reagents, we have recently started experiments directed toward elucidation of the stereochemistry of chiral allenes. The allenic moieties are frequently found in natural products as exemplified by fucoxanthin and kumausallene, the chemical components of algae. Because an allene has an axis of symmetry, it can exist as an enantiomer. To develop a new methodology for elucidating the absolute configurations of chiral allenes by means of NMR spectroscopy, a chiral nitrone was reacted with allenes by 1,3-dipolar addition, and the structure of the adducts was analyzed. 1,3-Dipolar addition of 5-methy1-5-phenylpyrroline N-oxide (1) to symmetrically or asymmetrically disubstituted allenes gave diastereomers. These were the compounds expected by electronic and steric factors. The stereochemistry of the products as well as the reaction profiles can lead to the absolute configuration of the original allenes.
天然有機化合物討論会の論文
2004-10-01