Superelectrophilic Activation of Alkynes, Alkenes, and Allenes

Abstract

Recent advances in organic synthesis based on superelectrophilic activation of alkynes, alkenes, allenes, and their trifluoromethyl substituted derivatives under the action of Brønsted superacids (CF3SO3H, FSO3H, HF), strong Lewis acids (AlCl3, AlBr3), conjugate Brønsted-Lewis superacids (CF3SO3H–SbF5, FSO3H–SbF5, HF–SbF5, HBr–AlBr3, HCl–AlCl3) or superacidic H+-zeolites are considered. These reactions proceed through an intermediate formation of carbocationic and other cationic species and lead to the formation of various functionalized compounds, carbocycles, heterocycles under mild conditions and in high yields of target products. In many cases, cationic reaction intermediates are detected and thoroughly studied by means of NMR in superacids (CF3SO3H, FSO3H), that help to prove reaction mechanisms.

Keywords: Acidic zeolites, Alkenes, Alkynes, Allenes, Brønsted superacids, Carbocations, Carbocycles, Cyclization, DFT calculations, Enynones, Friedel- Crafts reactions, Heterocycles, Hydroarylation, Ionic hydrogenation, Lewis acids, NMR of cations, Superelectrophilic activations, Trifluoromethyl group, Vinyl triflates.