Inhibition of tumor necrosis factor (TNF) production or function by small molecules has become a major focus in the pharmaceutical industry for the treatment of rheumatoid arthritis. In this study, a series of 39 novel SPD-304 analogs were designed, synthesized and evaluated as TNF inhibitors. Our results show that small structural changes produce ligands with similar binding affinities (Kd) for TNF, but significantly different potencies in a L929 cell-based assay. In addition, contrary to the high affinity of compounds 4e, 8c and 10e for TNF in vitro, the potency of these compounds was determined to be low. We propose that these differences can partly be explained by the physicochemical characteristics of the synthesized SPD-304 analogs. Our findings were supplemented by molecular docking studies on the TNF dimer. These synthesized analogs may serve as a starting point for developing novel TNF inhibitors.