Evidence was collected for the intermediate formation of thionium ions in Brønsted acid-catalyzed [2 + 2] photocycloaddition and electrophilic addition reactions to enone dithianes and dithiolanes. Low-temperature NMR studies helped to elucidate the structure and configuration of the thionium ions and thus support previous and current results obtained by UV/Vis spectroscopy.
Christoph Brenninger, Thorsten Bach. α-Thio Carbocations (Thionium Ions) as Intermediates in Brønsted Acid-Catalyzed Reactions of Enone-Derived 1,3-Dithianes and 1,3-Dithiolanes. Topics in catalysis. 2018;61(7):623-629
PMID: 30996580
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