InChI=1S/C19H20O4/c20-16-7-1-14(2-8-16)5-11-18(22)13-19(23)12-6-15-3-9-17(21)10-4-15/h1-5,7-11,19-21,23H,6,12-13H2/b11-5+/t19-/m1/s1