InChI=1S/C15H18O4/c1-7-4-11-9(8(2)14(18)19-11)5-15(3)6-10(16)13(17)12(7)15/h7,9,11,17H,2,4-6H2,1,3H3/t7-,9-,11-,15-/m0/s1