Spiro[furo[2',3':5,6]cyclohepta[1,2-b]pyran-6(2H),6'(5'H)-[2H]oxireno[4,5]cyclohepta[1,2-b]furan]-2,5'-dione,7-acetyl-1'a,3,3',3a,3'a,4,4a,6'a,7',7'a,8a,9,10,10a-tetradecahydro-8a-hydroxy-2',9-dimethyl-3-methylene-1'a-(3-oxo-1-butenyl)-,[3aR-[3aa,4aa,6b[1