InChI=1S/C15H20O6/c1-9(13(17)18)4-3-7-15(2,21)11-6-5-10(14(19)20)8-12(11)16/h5-6,8-9,16,21H,3-4,7H2,1-2H3,(H,17,18)(H,19,20)/t9?,15-/m0/s1