(1Z,5S,5aS,8Z,10bS,10cS)-1,8-dibutylidene-5,5a,6,7,8,10b-hexahydro-1H-5,10c-ethanonaphtho(1,2-c:7,8-c')difuran-3,10-dione
(1z,5s,5as,8z,10bs,10cs)-1,8-dibutylidene-5,5a,6,7,8,10b-hexahydro-1h-5,10c-ethanonaphtho(1,2-c:7,8-c')difuran-3,10-dione