33 動的速度論分割に基づく分子内不斉Heck反応とDichroanal類の不斉全合成(口頭発表の部)

概要

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(-)-Standishinal having abeoabietane skeleton, which was isolated from Thuja standishii by Tanaka, is natural product possessing inhibitory activity against aromatase. Recently, many diterpenoids having the same skeleton have been isolated. These diterpenoids are also expected to have promising activities as medicines for female hormone-dependent cancers. Here, we will report the efficient synthetic method applicable to synthesis of the various abeoabietane type diterpenoids. In the beginning, we investigated asymmetric construction of the abeoabietane skeleton possessing quaternary stereogenic center. We anticipated that intramolecular asymmetric Heck reaction of diene 1 afford the desired tricyclic product. Because 1 was predicted to exist as two atropisomers, diene 1 was not suitable substrate for asymmetric reaction. However, we found that the asymmetric Heck reaction of 1 afforded the abeoabietane type intermediate in good yield with high enantiomeric excess by dynamic kinetic resolution through equilibration between two atropisomers. This is the first example of the asymmetric Heck reaction by dynamic kinetic resolution. Next, we applied this novel asymmetric Heck reaction to an asymmetric synthesis of natural products and succeeded in the first asymmetric synthesis of (-)-dichroanal B, (-)-dichroanone, (-)-taiwaniaquinone H.
天然有機化合物討論会の論文
2008-09-01