11 簡單な天然有機化合物の簡單な合成II
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概要
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The concept of the simple synthesis which was examplified last year by the present author, is further demonstrated by the synthesis of two different series of alkaloids having an interesting skeletal structure (pyrrolidino [3,2-b] quinazolone and furo [2,3-b] indole). I Syntheses of Three Pyrrolidino [3,2-b] quinazolone Alkaloids A general and widely applicable threestep synthesis of pyrrolidino [3,2-b] quinazolone alkaloid has been established. Condensation of anthranilic acid and its derivative(10a,b) with O-methylbutyrolactim(14) proceeded readily to afford compounds(12a,b) with pyrrolidino [3,2-b] quinazolone ring system. The NBS bromination of these products, followed by the substitution with appropriate nucleophiles completed the synthesis with the production of acetylvasicinone(15a), anisessine(6), 16a-2 and "sessiflorine"(9). The identity of synthesized vasicinone(4) and anisessine with natural specimens confirms the position of the NBS bromination and proves the correctness of the proposed structure(6) of anisessine. Natural sessiflorine, on the contrary, is not identical with the synthesized sample posessing the structure(9). And the constitution previously assigned to sessiflorine is revised to 17 by the comparison of spectral data of synthesized and natural sessiflorine. II Synthesis of Furo [2,3-b] indole Alkaloid Physovenine(19) Consideration of general approach to the synthesis of furo and pyrro-[2,3-b] indole led us to examine a new type of construction of these ring systems utilizing the key reaction represented by the conversion from 23 to 24. The Grignard compound of 5-methoxyskatole(27) was reacted with ethylene oxide to furnish oily nor-physovenmethol(28), which could be readily methylated to physovenmethol(29). Two step convertion of 29 to physovenine(19) has already been achieved, and therefore our synthesis constitutes a formal five step synthesis of physovenine starting from p-methoxyphenylhydrazine.
- 天然有機化合物討論会の論文
- 1969-09-01