(2R,3aS,3bS,6aR,7aR)-4,4-Dichloro-2,3b-dimethyl-5-oxo-decahydro-cyclopenta[a]pentalene-2-carboxylic acid methyl ester

(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