Superacid‐Promoted Synthesis of CF 3 ‐Indenes Using Brominated CF 3 ‐Enones

The reactions of 3‐bromo‐ and 3,4‐dibromo‐CF 3 ‐enones with superacids were studied. Protonation of these CF 3 ‐enones with FSO 3 H resulted in the formation of cationic species that subsequently cyclized at –60 °C to give the corresponding mono‐ and dibromoindenols in up to 98 % yield. Protonation...

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Bibliographic Details
Published in:European journal of organic chemistry 2017-10, Vol.2017 (37), p.5632-5643
Main Authors: Iakovenko, Roman O., Kazakova, Anna N., Boyarskaya, Irina A., Gurzhiy, Vladislav V., Avdontceva, Margarita S., Panikorovsky, Taras L., Muzalevskiy, Vasiliy M., Nenajdenko, Valentine G., Vasilyev, Aleksander V.
Format: Article
Language:English
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Summary:The reactions of 3‐bromo‐ and 3,4‐dibromo‐CF 3 ‐enones with superacids were studied. Protonation of these CF 3 ‐enones with FSO 3 H resulted in the formation of cationic species that subsequently cyclized at –60 °C to give the corresponding mono‐ and dibromoindenols in up to 98 % yield. Protonation of the indenol products at room temperature with triflic acid (CF 3 SO 3 H) provided highly electrophilic trifluoromethylated indenyl cations. Subsequent reaction with various arenes gave access to 1‐CF 3 ‐substituted indenes in up to 84 % yields. DFT calculations were carried out to obtain data about the electronic structure and electrophilicity of the cationic intermediates. The mechanisms of these multistep transformations of highly electrophilic cationic intermediates are discussed.
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.201701085