光学活性アセタール類を利用する遠隔位不斉誘導反応の開発と天然物不斉合成への応用

Abstract

Intramolecular haloetherification of the ene acetals prepared from chiral non-racemic C2-symmetric diols and achiral 4-pentenal or 5-heptenal proceeded in diastereoselective manners to form two asymmetric centers. The reaction was applied to synthesize optically active 1,4- and 1,5-diols. On the other hand, intramolecular haloetherification of diene acetals proceeded in two different manners. The intramolecular haloetherification of the diene acetals, prepared from chiral hydrobenzoin and σ-symmetric cyclohexa-1,4-dienes, proceeded with one olefin in a diastereoselective manners and gave the compounds having one remained olefin. However, the reaction of the acyclic diene acetals, prepared from hydrobenzoin and σ-symmetric 1,7-dienes, occurred novel double haloetherification giving four newly formed chiral stereocenters. The developed reactions were applied to synthesize optically active natural products, a civet constituent, scyphostatin, (+)-Sch 642305, rublenolide and rubrynolide.