InChI=1S/C20H20O2/c1-2-3-4-5-6-7-8-13-18-14-9-10-15-19(18)16-11-12-17-20(21)22/h2-17H,1H3,(H,21,22)/b3-2+,5-4-,7-6+,13-8-,16-11+,17-12+