Development of Versatile Chiral Building Blocks from Meso-Enediol Compounds Utilizing Catalytic Asymmetrization Reactions

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The asymmetric olefin migration reaction catalyzed by cationic Rh-complex ligated with chiral BINAP had been successfully carried out for the meso type enediol silyl ether having bicyclo [2.2.1] ring system in its background and 7-membered ring system as substrates. However, applications of this reaction to the other simplified meso substrates (e.g.8-membered ring substrate or 6-membered ring substrates) did not gave satisfactory results. Therefore, the requirement to afford high selectivity of this asymmetric olefin migration reaction was suggested that at least some bulky ether subtituents are necessary at the both allylic positions.On the other hand, keto-silyl ether having high optical purity obtained by this methodology was applied to natural products syntheses. As a result, (-)-malyngolide, (-)-shikimic acid, (-)-quinic acid, (-)-zeylenol, (+)-pipoxide, (-)-uvarigranol G, (-)-isoretronecanl, (+)-trachelanthamidine, and two kinds of cyclohexenone derivatives could be synthesized as the optically active form. Furthermore, the proposed structure of (-)-tonkinenin A could be revised and (-)-epizeylenol could be disproved.