(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

(1R,3R,5S)-3-Methyl-bicyclo[3.2.0]hept-6-ene-3-carboxylic acid methyl ester

methyl (1S,3R,5S,6R)-3-methyl-6-hydroxybicyclo<3.2.0>heptane-3-carboxylate

methyl (1S,3R,5S)-3-methyl-6-oxobicyclo<3.2.0>heptane-3-carboxylate

(1R,3S,5S)-7,7-dichloro-3-methyl-6-oxobicyclo<3.2.0>heptane-3-carboxylic acid