NSC724778 [(1R,4S,5R,8S,12R,13R)-1,5-dimethyl-10-(trifluoromethyl)-11, 14,15,16-tetraoxatetracyclo[10.3.1.04,13.08,13]hexadec-9-en- 9-yl]methyl[1S,4R,5R,8R,12R,13S)-1,5-dimethyl-10-(trifluorom ethyl)-11,14,15,16-tetraoxatetracyclo[10.3.1.04,13.08,13]hex adec-9-en-9-yl]methyl ether