InChI=1S/C21H20O6/c1-10(2)17-20(27-17)13-5-6-15-16(19(13)24-4)21(23)25-9-12-7-11(3)8-14(22)18(12)26-15/h5-8,17,20,22H,1,9H2,2-4H3/t17-,20-/m1/s1