InChI=1S/C22H20O6/c1-11(2)15-9-14-16(27-15)10-17-18(19(14)23)20(24)22(26-4)21(28-17)12-5-7-13(25-3)8-6-12/h5-8,10,15,23H,1,9H2,2-4H3