title: Synthesis of pyrrolophenanthridine alkaloids based on C(sp³)-H and C(sp²)-H functionalization reactions.
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(sp(3))-H functionalization followed by a Catellani reaction, including C(sp(2))-H functionalization. A one-pot reaction involving both C(sp(3))-H and C(sp(2))-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.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida, Sakyo-ku, Kyoto 606-8501 (Japan), Fax: (+81) 75-753-4569.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tsukano
authors.forename: Nobusuke
authors.initials: N
authors.lastname: Muto
authors.forename: Iderbat
authors.initials: I
authors.lastname: Enkhtaivan
authors.forename: Yoshiji
authors.initials: Y
authors.lastname: Takemoto
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D015394:Molecular Structure; D010617:Phenanthridines / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000470:Alkaloids; D010617:Phenanthridines; D011758:Pyrroles; D002244:Carbon; D006859:Hydrogen
keywords: CH activation; alkaloids; natural products; synthesis design; total synthesis