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The Witkop Cyclization: A Photoinduced CH Activation of the Indole System
Author(s) -
Gritsch Philipp J.,
Leitner Christian,
Pfaffenbach Magnus,
Gaich Tanja
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201307391
Subject(s) - indole test , chemistry , intramolecular force , excited state , photochemistry , electron transfer , photoinduced electron transfer , redox , molecule , combinatorial chemistry , stereochemistry , organic chemistry , physics , nuclear physics
Investigations of excited‐state redox processes have an exceptional impact on the field of organic photochemistry and its application to the synthesis of complex target molecules. In such a photochemical process a single‐electron transfer takes place to produce ion‐radical intermediates, if the reduction and oxidation potentials, as well as excited‐state energies of electron donors and acceptors are chosen appropriately. The Witkop cyclization constitutes an intramolecular variant of such a process, typically with an indole heterocycle as an electron donor. The specific synthetic value of this reaction lies in a CC bond formation without requiring any prefunctionalization of the indole system. Although this photoreaction has been applied to the total synthesis of natural products, it has still not been used to its full capacity. The following review details synthetic efforts using the Witkop cyclization, and aims to incite further applications of reaction in the synthesis of complex molecular architectures.