InChI=1S/C21H28O4/c1-13(2)7-6-8-15(5)10-12-17-18(22)16(11-9-14(3)4)19(23)21(25)20(17)24/h7,9-10,23-24H,6,8,11-12H2,1-5H3/b15-10+