3,10,10c-Trimethyl-5-methylene-2,3,4b,5,6,7,10b,10c-octahydrooxireno[2'',3'':6',7']indeno[5',4':3,4]cyclohepta[1,2-b]furan-4(1aH)-one AIDS-136966 AIDS136966 NSC640326