In superacids with H0=− 14 to− 20, it has been found that 1, 3-diarylpropynones ArCCCOAr′ are either protonated on oxygen of carbonyl groups with the formation of stable ions ArCCC (O+ H) Ar′ or undergo further transformations when the highly conjugated system is electron-rich enough. In the latter case, 3-arylindenones are produced very rapidly and with high efficiency (up to 95% yield in less than 30 min). The influence of ...