(2S,4S)-1-[[N-(4-Carboxybicyclo[2.2.2]oct-1-yl)amino]acetyl]-4-fluoropyrrolidine-2-carbonitrile (30.0 mg), along with 1-hydroxybenzotriazole, was dissolved in N,N-dimethylformamide (1.0 mL). While the solution was chilled in an ice bath, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (53.4 mg) was added and the mixture was allowed to warm to room temperature and was stirred for 1 hour. Subsequently, 4-fluoroaniline (17.8 μL) was added and the mixture was stirred for additional 2 hours. The solvent was evaporated under reduced pressure and the resulting residue was purified by preparative thin-layer chromatography (solvent:dichloromethane:methanol=4:1) to give (2S,4S)-4-fluoro-1-[[N-[4-[N-(4-fluorophenyl)amino]carbonylbicyclo[2.2.2]oct-1-yl]amino]acetyl]pyrrolidine-2-carbonitrile (14.6 mg).
