Synthesis of Pyrrolophenanthridine Alkaloids Based on C(sp3)H and C(sp2)H Functionalization Reactions |
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| Authors: | Dr. Chihiro Tsukano Nobusuke Muto Iderbat Enkhtaivan Prof. Yoshiji Takemoto |
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| Affiliation: | Graduate School of Pharmaceutical Sciences, Kyoto University, 46‐29 Yoshida, Sakyo‐ku, Kyoto 606‐8501 (Japan), Fax: (+81)?75‐753‐4569 |
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| Abstract: | Assoanine, pratosine, hippadine, and dehydroanhydrolycorine belong to the pyrrolophenanthridine family of alkaloids, which are isolated from plants of the Amaryllidaceae species. Structurally, these alkaloids are characterized by a tetracyclic skeleton that contains a biaryl moiety and an indole core, and compounds belonging to this class have received considerable interest from researchers in a number of fields because of their biological properties and the challenges associated with their synthesis. Herein, a strategy for the total synthesis of these alkaloids by using C? H activation chemistry is described. The tetracyclic skeleton was constructed in a stepwise manner by C(sp3)? H functionalization followed by a Catellani reaction, including C(sp2)? H functionalization. A one‐pot reaction involving both C(sp3)? H and C(sp2)? H functionalization was also attempted. This newly developed strategy is suitable for the facile preparation of various analogues because it uses simple starting materials and does not require protecting groups. |
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| Keywords: | alkaloids C H activation natural products synthesis design total synthesis |
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