Organic isothiocyanates (ITCs) are a class of anticancer agents which naturally result from the enzymatic degradation of glucosinolates produced by Brassica vegetables. Previous studies have demonstrated that the structure of an ITC impacts its potency and mode(s) of anticancer properties, opening the way to preparation and evaluation of synthetic, non‐natural ITC analogues. This study describes the preparation of a library of 79 non‐natural ITC analogues intended to probe further structure‐activity relationships for aryl ITCs and second‐generation, functionalized biaryl ITC variants. ITC candidates were subjected to bifurcated evaluation of antiproliferative and antioxidant response element (ARE)‐induction capacity against human MCF‐7 cells. The results of this study led to the identification of (1) several key structure‐activity relationships and (2) lead ITCs demonstrating potent antiproliferative properties.