酸素の孤立電子対を利用する高立体選択的反応の開発

抄録

  Highly stereoselective reactions have been developed using lone pairs of oxygen atoms, in other words, the nucleophilic ability of oxygen atoms. They consist of five types of reactions: 1) asymmetric synthesis using acetals, 2) organic reactions via Beckmann fragmentation intermediates, 3) organic reactions via dication equivalents, 4) rearrangement of 2,3-epoxy-1-alcohol derivatives, and 5) organic reactions using orthoesters. In this review, asymmetric syntheses using acetals are described in detail. They are divided into four categories: 1) diastereoselective 1,2-addition(alkylation, reduction) to the α-keto acetals and their derivatives, 2) asymmetric carbon-carbon bond formation by a combination of Beckmann fragmentation and asymmetric synthesis using C₂-symmetric chiral acetals, 3) asymmetric synthesis via chiral oxonium ions prepared by intramolecular haloetherification of chiral ene acetals having C₂-symmetric hydrobenzoin, and 4) asymmetric desymmetrization of meso-1,2-, meso-1,3-, and meso-1,4-diols via chiral oxonium ions prepared by intramolecular haloetherification of chiral ene acetals derived from optically pure norbornen aldehyde derivatives, and their applications to asymmetric syntheses of biologically active natural products.