Novel generation of 9H-furo[3,2-b]chromen-9-ones from (E)-3-hydroxy-2-styrylchromones by excited state intramolecular proton transfer

Photocyclisation of substituted （E）-3-hydroxy-2-（V-methyl-2＇-phenylvinyl）-4-oxo-4H-1-benzopyrans to yield linear novel tricyclic 9H-furo[3,2-b]chromen-9-ones and angular fused tetracyclic xanthenones is described.