1,3-dihydroxy-11H-[1]benzofuro[2,3-b]chromen-11-one 11H-benzofuro[2,3-b][1]benzopyran-11-one, 1,3-dihydroxy- InChI=1/C15H8O5/c16-7-5-9(17)13-11(6-7)20-15-12(14(13)18)8-3-1-2-4-10(8)19-15/h1-6,16-17