InChI=1S/C21H20O6/c1-20(2,22)18-7-11-6-13-16(9-15(11)26-18)25-10-21(23)14-5-4-12(24-3)8-17(14)27-19(13)21/h4-9,19,22-23H,10H2,1-3H3