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Superacid‐Promoted Synthesis of CF 3 ‐Indenes Using Brominated CF 3 ‐Enones
Author(s) -
Iakovenko Roman O.,
Kazakova An.,
Boyarskaya Irina A.,
Gurzhiy Vladislav V.,
Avdontceva Margarita S.,
Panikorovsky Taras L.,
Muzalevskiy Vasiliy M.,
Nenajdenko Valentine G.,
Vasilyev Aleksander V.
Publication year - 2017
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.201701085
Subject(s) - chemistry , protonation , electrophile , cationic polymerization , superacid , triflic acid , medicinal chemistry , yield (engineering) , organic chemistry , catalysis , ion , materials science , metallurgy
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.