Synthesis, structure-activity relationship, and evaluation of SR141716 analogues: development of central cannabinoid receptor ligands with lower lipophilicity

Exploration of the central CB1 cannabinoid receptors using positron emission tomography (PET) will allow for an understanding of the pharmacological and physiological role played by these receptors in the CNS. Current tracers are highly lipophilic compounds that exhibit very high nonspecific to specific binding ratios and as a result are inapt for use in humans. We have synthesized a series of less lipophilic analogues of SR141716 to serve as potential radioligands. Binding affinities of the series and a functional electrophysiological assay of three of our compounds have been presented.