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Synthesis of Pyrrolophenanthridine Alkaloids Based on C(sp 3 )H and C(sp 2 )H Functionalization Reactions
Author(s) -
Tsukano Chihiro,
Muto Nobusuke,
Enkhtaivan Iderbat,
Takemoto Yoshiji
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201402490
Subject(s) - surface modification , moiety , chemistry , indole test , stereochemistry , combinatorial chemistry
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 CH 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.