Recently, we reported the synthesis and biochemical studies of a series of (pO-sulfamoyl)-N- alkanoyl tyramines as nonsteroidal estrone sulfatase inhibitors. One of the most potent inhibitors in this series is (pO-sulfamoyl)-N-tridecanoyl tyramine 1 with an IC50 value of 61.3 nM. In this study, we synthesized four analogs of 1 (compounds 2–5) to investigate the structure-activity relationships of the amide functionality in (pO-sulfamoyl)-N-tridecanoyl ...