Reactions of 3-Arylpopynoic Acid Amides with Arenes in Trifluoromethanesulfonic Acid

Abstract

3-Arylpropynoic acid amides [Ar–C≡C–CONR₂] in reactions with benzene and electron-donating arenes Ar′H in Brønsted superacid CF₃SO₃H (trifluoromethanesulfonic acid, TfOH) give products of mainly anti-hydroarylation of acetylene bond, amides of 3,3-diarylpropenoic acids [Ar(Ar′)C=CHCONR₂], at room temperature for 1 h with yields of 38–95%. The reactive intermediates of this reaction, O,C-diprotonated forms of amides of 3-arylpropynic acids [Ar–C⁺=CH–C(=O+H)NR₂], have been studied by quantum chemistry using density functional theory (DFT). According to calculations, the reactive vinyl cationic center in these particles carries a significant positive charge (0.37–0.44 e) and makes a substantial contribution to the HOMO (25.3–37.8%).