(2R*,3aS*,3bR*,7aR*)-2,3,3a,3b,4,5,7,7a-octahydro-2,3b-dimethyl-5-oxo-1H-cyclopentapentalene-2-carboxylic acid

methyl (2S,3aR,3bS,7aS)-2,3,3a,3b,4,5,7,7a-octahydro-2,3b-dimethyl-5-oxo-1H-cyclopentapentalene-2-carboxylate

(2S,3aR,3bS,7aS)-4-[1-Hydroxy-meth-(Z)-ylidene]-2,3b-dimethyl-5-oxo-2,3,3a,3b,4,5,7,7a-octahydro-1H-cyclopenta[a]pentalene-2-carboxylic acid