Acid-Catalyzed Cascade Ring-Opening and Addition Reactions of Arylvinylcyclopropenes with α,β-Unsaturated Substrates, Scope and Limitations

Catalyzed by Al(III) catalyst, arylvinylcyclopropenes react with alpha,beta-unsaturated substrates smoothly to produce the Diels-Alder adducts in moderate to good yields through a cascade ring-opening reaction/Diels-Alder cycloaddition. On the other hand, strong Bronsted acid TfOH can promote the cascade intramolecular Friedel-Crafts/1,4-addition reaction to produce indene derivatives in moderate to good yields under mild conditions, The acidity of the catalysts plays a key role in these reactions.