Reactions of 3-arylpropenenitriles with arenes under superelectrophilic activation conditions: Hydroarylation of the carbon-carbon double bond followed by cyclization into 3-arylindanones

Reactions of 3-arylpropenenitriles [ArCH=CHCN] with arenes [Ar'H] under the superelectrophilic activation conditions with Bronsted superacid TfOH (CF3SO3H) or strong Lewis acid AIBr(3) result, first, in the formation of products of hydroarylation of the carbon-carbon double bond, 3,3-diarylpropanenitriles [Ar(Ar')CHCH2CN]. Reactions may go further in TfOH leading to 3-arylindanones, as products of intramolecular aromatic acylation by the electrophilically activated nitrile group. Intermediate cationic species, derived at the protonation of the starting 3-arylpropenenitriles onto the carbon of C=C bond and the nitrile nitrogen, have been studied by DFT calculation. A plausible reaction mechanism including the formation of highly reactive dications [(Ar)HC+-CH2C+ = NH] has been proposed. The obtained 3,3-diarylpropanenitriles have been transformed into pharmaceutically valuable 5-(2,2-diarylethyl)-1H-tetrazoles [Ar(Ar')CHCH(2)Tetr] and 3-diarylpropylamines [Ar(Ar')CH(CH2)(2)NH2] by the reactions with NaN3 and LiAIH(4) correspondingly. (C) 2020 Elsevier Ltd. All rights reserved.