Reactions of 3-functionalized chromones with triacetic acid lactone

Reaction of 3-formylchromones and triacetic acid lactone proceeds with retention of the chromone skeleton and cyclization into pyrano[3′,4′:5,6]pyrano[2,3-b]chromene system. The crystal structure of the reaction product from unsubstituted 3-formylchromone has been determined from X-ray data. Other chromone analogues bearing CO₂H, CO₂Me and CN substituents react with triacetic acid lactone affording an o-hydroxychalcone heteroanalogue, pyrano[3,2-c]chromene and chromeno[2,3-b]pyridine derivatives, respectively.