Syntheses of thienylamphetamine derivatives via borane chemistry

Single-Photon-Emission Computed Tomography (SPECT) is a medical imaging technique which provides three-dimensional images of living systems after infusion of radiolabeled chemical compounds. Iodine-123 labeled N-isopropyl p-iodoamphetamine (IMP) has been evaluated in humans as an imaging agent for use with SPECT, and shows a high brain uptake coupled with slow washout. The current synthesis of IMP has limitations which include an inefficient labeling exchange reaction and the presence of high concentrations of unlabeled material in the final product. The substitution of thiophene for the benzene ring in the amphetamine could provide a more straightforward approach to halogenated amphetamines due to the greater reactivity of heterocycles to electrophilic ring substitutions with halogens.

Iodine-131 labeled N-isopropyl 2-(2-aminopropyl)-5-iodothiophene was prepared via borane chemistry for studies as a potential substitute for the labeled N-isopropyl p-iodoamphetamine.