Scale-Up Synthesis of the Dopamine Uptake Inhibitor GBR-12909

1-[2-[Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR-12909) is a dopamine uptake inhibitor. The development of a robust process for the preparation of this compound in kilogram quantities is described. The primary aims of the development work were to eliminate chromatographic purifications, to minimize the use of environmentally unacceptable reagents, and to improve the overall yield of the three-step convergent process. These objectives were met, with significant improvements obtained in the key coupling reaction of N-(3-phenylpropyl)piperazine dihydrochloride salt with 1-[bis(4-fluorophenyl)methoxy]-2-chloroethane, which was previously low-yielding and lacking in reproducibility.