(1aR,5aR,7aS,8R,10cR)-5a,7a-dimethyl-1,1a,3',4,4',5,5a,5b,6,7,7a,9,10,10a,10b,10c-hexadecahydro-3H,5'H-spiro[cyclopenta[a]cyclopropa[l]phenanthrene-8,2'-furan]-3,5'-dione [ 40574-52-5 ]