Different reactivities of acetylene carbonyl compounds under the catalysis by Bronsted superacids and Lewis acids Original Research Article

Acetylene carbonyl compounds ArCtriple bond; length of mdashCCOR (R = H, Me, Ph) form vinyl cations ArC+double bond; length as m-dashCHCOR or ArC+double bond; length as m-dashCHC(OH)+R at the protonation in Bronsted and conjugate Bronsted–Lewis superacids (protic superacids: HSO3F, CF3SO3H, HSO3F–SbF5, CF3SO3H–SbF5, HAlBr4) with a wide range of acidity (Ho ∼ −11 to −22). The vinyl cations react with arenes Ar’H with the formation of alkenylation products ArAr’Cdouble bond; length as m-dashCHCOR. On the contrary to protic superacids Lewis acids (AlBr3, AlCl3) activate additionally electrophilic center at carbonyl carbon of the compounds ArCtriple bond; length of mdashCCOR that leads to the formation of substituted indenes in their reactions with arenes.