4,5-Dioxo-1-p-tolyl-cyclopentane-1,3-dicarboxylic acid diethyl ester
3-ethyl-2-hydroxy-2-cyclopenten-1-one
3-(2,4-dinitro-phenylhydrazono)-7,8,9-trimethoxy-5-oxo-1,2,3,5-tetrahydro-cyclopent[c]isochromene-2-carboxylic acid methyl ester
cyclopentane-1,2-dione-bis-phenylhydrazone
2,5-dimethyl-2-p-tolyl-2-cyclopentanone