The lithium enolate of the indanone derivative (I) is fluorinated by treatment with N-fluorobenzenesulfonimide, to afford the corresponding fluoro ketone, which is finally isolated as the corresponding hydrochloride salt.

The title compound is also prepared by a related method. Indanone (I) is fluorinated by means of N-fluorobenzenesulfonimide in the presence of lithium hexamethyldisilazide, to afford the corresponding fluoro ketone (II). Subsequent dealkylation of the N-benzyl group of (II) is accomplished by treatment with 1-chloroethyl chloroformate, to produce the intermediate carbamate (III), which is then decarboxylated to the secondary amine (IV) in boiling MeOH. Finally, piperidine (IV) is reductively alkylated with 3-fluorobenzaldehyde (V) in the presence of NaBH(OAc)3.