InChI=1S/C20H20O7/c1-7-6-9(21)11-12-10(7)18-20(25,19(3,4)8(2)27-18)17(24)13(12)15(23)16(26-5)14(11)22/h6,8,22-23,25H,1-5H3/t8-,20+/m1/s1