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

(3aS,5S,6aR)-5-Methyl-1-oxo-octahydro-pentalene-2,5-dicarboxylic acid 2-ethyl ester 5-methyl ester