(3S,3aR,4R,4aS,8aR,9S,9aR)-4,9-epoxy-3-ethyl-decahydronaphtho[2,3-c]furan-1(3H)-one

(3S,3aS,4R,4aS,8aR,9aS)-decahydro-4-hydroxy-3-ethylnaphtho[2,3-c]furan-1(3H)-one

(1S,3S,3aS,4R,4aS,8aR,9aS)-3-ethyl-dodecahydro-1-methoxynaphtho[2,3-c]furan-4-ol

(1S,3S,3aS,4aS,8aR,9aS)-3-ethyl-dodecahydro-1-methoxy-4-methylenenaphtho[2,3-c]furan

(1S,3S,3aR,4R,4aS,8aR,9aS)-3-ethyl-dodecahydro-1-methoxynaphtho[2,3-c]furan-4-methanol