81957-73-5 Angeolide NSC382181 Spiro[3H-3a,6-ethanoisobenzofuran-4(1H),1'(3'H)-isobenzo furan]-1,3'-dione, 3-butylidene-5,6,6',7'-tetrahydro-5-propyl-, (3E,3aS,4S,5S,6R)-