(4S)-5-[(1a'R,2R,3'S,3a'R,4'R,7a'S,10a'S)-4'-(acetyloxy)-1a',3a',7a',8',9',10a'-hexahydro-2'H,4'H-dispiro[oxirane-2,10'-oxireno[6,7]cyclonona[1,2-c]pyran-3',2''-oxiran]-7'-yl]-2-methylpent-2-ene-4,5-diyl diacetate