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Straightforward Synthesis of Aromatic Polycyclic Terpenoids through Biomimetic Cascade Cyclizations Triggered by Photochemical Electron Transfer
Author(s) -
Rosales Viale,
Zambrano Jorge,
Demuth Martin
Publication year - 2004
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300585
Subject(s) - chemistry , moiety , photochemistry , cationic polymerization , photoinduced electron transfer , cascade , electron transfer , radical cyclization , markovnikov's rule , cascade reaction , radical ion , stereochemistry , combinatorial chemistry , organic chemistry , regioselectivity , catalysis , ion , chromatography
Photoinduced biomimetic cascade cyclizations of suitably functionalized terpenoid arylpolyalkenes via radical cationic intermediates represent a powerful route to polycyclic compounds in a single operational step. In all cases examined, the radical cation, created selectively and exclusively at the ψ‐polyalkene position, is trapped in anti ‐Markovnikov fashion by water, liberating a free radical site, which ultimately initiates cascade‐style bond formation to afford the all‐chair polycyclic conformation containing one aromatic moiety. The products, some of which are podocarpic‐type structures 17 − 19 , are beneficially 3β‐hydroxylated. Mechanistically, the reaction is probably initiated by a radical cation trapped by water prior to the cyclization event, which is driven by a pure radical‐type process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)