Synthesis of linear diphenyl furanocoumarins

The elegant and direct synthesis of linear 2′-3′-diphenyl furanocoumarins is recorded for the first time by submitting the desyl ether of hydroxycoumarins to the action of mild 0·1 N KOH. This reagent brings about aldol condensation followed by cyclisation and dehydration in the presence of acids as proposed by Macleod and Worth to give the desired linear diphenyl furanocoumarins in good yield.