InChI=1S/C21H30O4/c1-3-5-7-9-11-16-25-21(23)19-14-12-13-18(17-19)20(22)24-15-10-8-6-4-2/h6,8,12-14,17H,3-5,7,9-11,15-16H2,1-2H3/b8-6+