9 Jervineの全合成

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This report describes the results obtained in studies aimed at the total synthesis of jervine (I), a representative compound of C-nor-D-homosteroid alkaloids. This program involves the synthesis of dihydroveratramine (VI) and its transformation into I. The starting substances for preparation of the ring E and the remaining steroid part in VI were XIV and V, respectively, the latter having been derived from hecogenin, a totally synthesized sapogenin. XIV was converted into XVIII (Chart II), and V into VIII (Chart I). Condensation of XIII with an enamine of XVIII produced no satisfactory results from the viewpoint of yield and purity of the products. However, an expected product XXII was obtained from VI and available for further syntheses; treatment of XXII with alkali led to an equilibrium of XXII and its epimer XXIII (3: 1), and the latter was reconverted into VI (Chart III). Reduction of VI with lithium in ethyl amine followed by catalytic hydrogenation gave XXVI, which had been prepared from 11-deoxojervine (III). Oxidation of XXVI followed by alkali treatment and so on has now resulted in the formation of XXXII (Chart IV), which was also derived from III (Chart V). Difficulty was encountered in introduction of an oxygen function to C-11, and attempted oxidations have not completely been successful yet. Nevertheless, an expected oxidation product XXXVI could be derived from I (Chart VI) and used for subsequent reactions. Treatment of a 3-ketone IL, obtained from XXXVI (Chart VI), with DDQ afforded a dienone ILII, which in turn was converted into I (Chart VII). Transformations of I into other naturally occurring jerveratrum alkaloids, veratramine (II), III and verarine (IV), have been established.
天然有機化合物討論会の論文
1966-09-15

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