Synthesis of novel 2H,8H-pyrano[2,3-f]chromene-2,8-diones from 8-formyl-7-hydroxy-4-methylcoumarin

We report the synthesis of novel 2H,8H-pyrano[2,3-f]chromene-2,8-dione based scaffolds by the reaction of 8-formyl-7-hydroxy-4-methylcoumarin with various active methylene compounds. A mechanism of a tandem Knoevenagel condensation and cyclisation reaction is proposed. The structure of all compounds was established on the basis of 1H and 13C NMR data, high resolution mass spectrometry and elemental analysis.