InChI=1S/C21H28O4/c1-7-13(5)9-19(22)25-18-10-16(12(3)4)20-15(8-2)21(23)24-11-17(20)14(18)6/h8-10,12,17-18,20H,6-7,11H2,1-5H3/b13-9+,15-8-