32 ビシクロ対称ジケトンの酵母還元産物を共通のキラルビィルディングブロックとした天然物合成(口頭発表の部)

概要

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We have used baker's yeast reduction for the synthesis of optically active natural products. We extended this concept to bicyclo[2.2.2]octane ring system, and obtained enantiomerically pure β-hydroxy ketone A (>99%e.e.). We carried out the syntheses of pinthunamide (1), bergamoten-12-oic acids (α-form: 2, β-form: 3), and homogynolide A (4) by employing A as a common chiral starting material. The key reaction in the syntheses of 1,2, and 3, was the intramolecular alkylation to generate the four-membered ring (5a→6a, 5b→6b), which can be a general method to prepare pinane-type ring systems. Oxy-Cope rearrangement (27→26) was employed as an important step in the synthesis of 4, which was the ring transformation from bicyclo[2.2.2]octane to bicyclo[3.3.0]octane system. In summary, we demonstrated the utility of the β-hydroxy ketone A as a chiral building block for the syntheses of several natural products.
天然有機化合物討論会の論文
1994-09-20