Organic Brønsted acid‐catalyzed cycloadditions of o‐quinone methides with 1, 3‐dicarbonlys: Facile access to xanthenones and chromanones.

The in‐situ generation of o‐quinone methides and their inverse‐electron‐demand Diels–Alder reaction in the presence of pentacarboxycyclopentadiene—an organic Brønsted acid—has been reported. The synthesis of xanthenones and chromanones in good to excellent yields from the [4 + 2] cycloaddition of quinone methides with 1, 3‐dicarbonyls and Meldrum's acid has been accomplished. The development of this method helps in generating a number of biologically potent heterocycles with medicinal applications. [ABSTRACT FROM AUTHOR]