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Brønsted Acid Catalysis in Visible‐Light‐Induced [2+2] Photocycloaddition Reactions of Enone Dithianes
Author(s) -
Brenninger Christoph,
Pöthig Alexander,
Bach Thorsten
Publication year - 2017
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.201700837
Subject(s) - cyclobutanes , enone , moiety , chemistry , photochemistry , intramolecular force , catalysis , dithiane , visible spectrum , acid catalysis , brønsted–lowry acid–base theory , cycloaddition , medicinal chemistry , stereochemistry , organic chemistry , materials science , optoelectronics
Abstract 1,3‐Dithiane‐protected enones (enone dithianes) were found to undergo an intramolecular [2+2] photocycloaddition under visible‐light irradiation ( λ =405 nm) in the presence of a Brønsted acid (7.5–10 mol %). Key to the success of the reaction is presumably the formation of colored thionium ions, which are intermediates of the catalytic cycle. Cyclobutanes were thus obtained in very good yields (78–90 %). It is also shown that the dithiane moiety can be reductively or oxidatively removed without affecting the photochemically constructed ring skeleton.