InChI=1S/C20H28O4/c1-14(8-7-9-15(2)21)10-11-18-19(4,5)12-17(24-16(3)22)13-20(18,6)23/h7-10,17,23H,12-13H2,1-6H3/b9-7+,14-8+/t11?,17-,20+/m0/s1