Multicomponent one-pot reactions: synthesis of some new 6-oxopyrano [2,3-c]isochromenes by condensation of homophthalic anhydride, dialkyl acetylenedicarboxylate, and isocyanides.

A novel three-component, one-pot condensation of the zwitterion generated from dialkyl acetylenedicarboxylate and isocyanides with homophthalic anhydride is described. The reaction affords new 6-oxopyrano[2,3-c]isochromenes in good yield. Isochromenes have been reported to possess diverse biological activities such as antibacterial, antifungal, antiinflammatory, and antiangiogenic effects. Moreover, Theses important compounds are found in various natural products.