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

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

methyl (2S,3aR,6aS)-1,2,3,3a,4,5,6,6a-octahydro-2-methyl-4-oxopentalene-2-carboxylate

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

methyl (1S,2aR,2bR,2cR,4S,5aR,5bS,5cS)-1-(benzoyloxy)-decahydro-4,5b-dimethyl-2-oxo-1H-cyclopenta[a]cyclopropa[cd]pentalene-4-carboxylate