InChI=1S/C18H20O4/c1-10-6-5-7-18(2)9-12-11(8-13(10)18)14(19)16(21-3)17(22-4)15(12)20/h5,7,13H,1,6,8-9H2,2-4H3/t13-,18+/m1/s1