Reaction of 4-aryl-1,1,1-trifluorobut-3-en-2-ols
[CF3-allyl alcohols, ArCH=CHCH(OH)CF3] with arenes
under activation with anhydrous FeCl3 or FSO3H was studied.
We found that the transformation led to trifluoromethylated
alkenes [Ar(Ar′)CHCH=CHCF3] or 1-trifluoromethylated
indanes (CF3-indanes). The formation of these two types of reaction products strongly depends on the nucleophilicity of the
starting arene and the electrophilicity of cationic intermediates generated from CF3-allyl alcohols under reaction conditions.
Benzene, anisole, veratrole, and ortho-xylene lead exclusively to CF3-alkenes with an E-configuration. More π-donating
polymethylated arenes (pseudocumene, mesitylene) afford only CF3-indanes with a predominantly cis-orientation of substituents
at positions 1 and 3 of the indane ring. Meta- and para-xylenes show an intermediate behavior; they may form both CF3-alkenes
and/or CF3-indanes. The mechanisms of the investigated transformations are discussed.