[4+2] Cycloaddition reactions of coumarin quinone methide with pentafulvenes: facile synthesis of novel polycyclic pyran derivatives

The quinone methide generated in situ by the Knoevenagel condensation of formaldehyde and 4-hydroxycoumarin underwent facile Diels–Alder reactions with pentafulvenes to afford novel pyranocoumarin derivatives in good yields.