InChI=1S/C20H22O4/c1-24-20-14-16(9-13-19(20)23)8-12-17(21)5-3-2-4-15-6-10-18(22)11-7-15/h3,5-7,9-11,13-14,22-23H,2,4,8,12H2,1H3/b5-3+