71 Tabersonineの化学変換反応

概要

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A Japanese Apocynaceae plant, Amsonia elliptica Roem. et Schult, contains tabersonine (3) and the biogenetically related minor bases in the seeds. 3-Oxo-tabersonine (4), which is one of the minor bases and is also derivable from tabersonine through KMnO_4 oxidation, was converted to a vincamine type compound (21). The main product, however, was α-keto ester (22). In this case, a slow rearrangement of 20 to 21 allowed a further step of oxidation to take place to give 22. An attempt was made to convert an aspidosperma skeleton to that of Melodinus alkaloids along the proposed biogenetic route. 3-Oxo-tabersonine (4), in which the tertiary nitrogen of tabersonine was converted to an amide function, was used as the starting material. Under neutral conditions a rearrangement product (31) of an unnatural structural skeleton was obtained. The structure of 31 was elucidated on the chemical and spectral bases. Some anomalous properties of this product were pointed out. As a result, the initial object to obtain the framework of Melodinus alkaloids remained to be studied further.
天然有機化合物討論会の論文
1979-09-20