Cocaine abuse is a major public concern, and current treatment strategies are in early stages with unestablished efficacy. Cocaine's behavioral properties, including its reinforcing effect, stem from inhibiting dopamine reuptake, but the precise mechanism remains unclear. Studies suggest the cocaine binding domain on the dopamine transporter is distinct from that of dopamine or amphetamine, enabling potential design of drugs that prevent cocaine binding without inhibiting dopamine uptake. Based on SAR work, the authors explored the effect of methoxylation of cocaine's two-carbon bridge on its binding and functional activity. Using Willstätter's chemistry, racemic 6- and 7-methoxy-substituted analogues of cocaine and pseudococaine (7-11) were synthesized, and their structures were characterized by NMR and X-ray analysis. Binding and dopamine uptake data showed methoxylation reduced activity by 10-100-fold. Compound 11 caused a concentration-dependent rightward shift of the cocaine inhibition curve, statistically greater than the theoretical value, suggesting it may be a weak functional antagonist of cocaine. The mechanism is unknown, but these findings indicate modifying cocaine's structure could lead to more robust antagonism via a novel mechanism. Synthesis and study of optically pure 11 are ongoing.