Ethyl isonipecotate (I) was protected as the N-trityl derivative (II) using triphenylmethyl chloride and triethylamine. Addition of Grignard reagent (IV) (prepared from 1-bromo-4-fluorobenzene (III) and magnesium in Et2O) to (II) produced the diaryl carbinol (V). Alcohol dehydration with simultaneous trityl group cleavage under acidic conditions yielded 4-[bis(4-fluorophenyl)methylene]piperidine (VI). 4-Chlorobutyrylpyrrolidine (IX), prepared by coupling of 4-chlorobutyryl chloride (VII) and pyrrolidine (VIII), was then condensed with piperidine (VI) to yield the target compound.