InChI=1S/C21H22O4/c1-14(2)9-11-16-17(12-10-15-7-5-4-6-8-15)20(21(23)24)18(22)13-19(16)25-3/h4-10,12-13,22H,11H2,1-3H3,(H,23,24)/b12-10+