(1R,2R,2'R,5R,5'S,6'S,8S,12R,14E,17R,18E,20E,24S)-6'-[(2E)-but-2-en-2-yl]-2,24-dihydroxy-4'-[(E)-methoxyazanylidene]-3,5',15,17-tetramethyl-3',4',5',6'-tetrahydrospiro[7,11,23-trioxatetracyclo[19.2.1.18,12.05,24]pentacosa-3,14,18,20-tetraene-10,2'-pyran]-6-one