InChI=1S/C21H34/c1-3-5-6-7-8-9-19-12-16-21(17-13-19)20-14-10-18(4-2)11-15-20/h10-11,14-15,19,21H,3-9,12-13,16-17H2,1-2H3/t19-,21?