InChI=1S/C21H18O6/c1-21(2)4-3-10-13(22)6-17-18(20(10)27-21)19-12(8-23-17)11-5-15-16(25-9-24-15)7-14(11)26-19/h3-7,12,19,22H,8-9H2,1-2H3