11 Pd触媒を用いる環形成反応を機軸とした(-)-Strychnineの全合成(口頭発表の部)

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(-)-Strychnine, which is the most famous of the Strychnos alkaloids, has seven rings and six asymmetric centers in the molecule and is one of the most complex natural products in its size. Although Woodward succeeded in the total synthesis of (-)-strychnine in 1954, there were no reports on the total synthesis of strychnine for about 40 years. Herein we report the total synthesis of (-)-strychnine. The synthesis of a chiral indoline derivative having the ABC-rings of (-)-strychnine was achieved by palladium-catalyzed asymmetric allylic substitution of a cyclohexenol derivative having substituent at the 2-position followed by palladium-catalyzed cyclization. Construction of the D-ring of (-)-strychine was carried out through palladium-catalyzed allylic oxidation. The G-ring and then the E-ring were constructed by palladium-catalyzed cyclization using Pd(OAc)_2. (+)-Isostrychnine was converted into (-)-strychnine by the known method. The spectral data and [α]_D values agreed with those of (+)-isostrychnine and (-)strychnine reported in the literature. The fact that all cyclizations for synthesis of (+)-isostrychnine were performed using palladium catalysts is indicated the importance of palladium catalyst in modern synthetic organic chemistry.
天然有機化合物討論会の論文
2002-09-01