Synthesis of functionalized chromenes using ketones and aldehyds

An efficient synthesis of 4-alkyl-4-methyl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-dione or 4-aryl-3,4- dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones via reaction of 4-hydroxycoumarin with Meldrum’s acid and ketones or aldehydes is described.