We report the synthesis and characterization of a variety of trans-3,4-substituted cyclopentanones and the corresponding tosylhydrazone derivatives starting with diethyl fumarate. Protection of the keto group followed by selective monohydrolysis of esters was achieved, resulting in cyclopentanones with different substituents at positions 3 and 4. The tosylhydrazone derivative of each cyclopentanone intermediate was prepared in moderate to good yields. These compounds are potential precursors for functionalized methanofullerenes.