13 アルケニルエチレングリコール基質の香月-シャープレス反応と天然物合成への活用(口頭発表の部)

概要

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Unprecedented high enantiospecific epoxidation of alkenylethylene glycol substrates under the Katsuki-Sharpless asymmetric conditions has been first recognized. Both dissymmetric and symmetric (C_2 and Cs) substrates underwent facile epoxidation in highly enantio- and diastereo-specific manners with inversed selection modes established in the conventional allylic alcohol substrates. Thus, dissymmetric and C_2-symmetric substrates afforded the corresponding epoxides in inversed enantio- and diastereo-selection modes, while C_2 (meso)-symmetric substrate afforded the epoxide in inversed enantioselection mode. Moreover, complete enantio- and diastereo-selective discrimination of two chemically equivalent vinyl groups in 2,2-bis-vinylethylene glycol substrate has also been observed under the epoxidation conditions. The observed stereochemical outcome, especially, that observed with the C_2 (meso) and the 2,2-bis-divinyl substrates, seemed to support that the monomer mechanism rather than the dimer mechanism is involved in the reaction of the 2-alkenyl-1,2-ethyleneglycol substrates. As a practical application of the present finding, a new enantiocontrolled synthesis of L-erythro- and D-threo-sphingosines has been established using the epoxides obtained from the C_2- and the Cs-symmetric substrates, respectively.
天然有機化合物討論会の論文
1991-09-07