Efficient preparation of (R)-2-(2,5-difluorophenyl)pyrrolidine via a recycle process of resolution.

An efficient preparation of (R)-2-(2,5-difluorophenyl)pyrrolidine ((R)-1) from the racemate based on a recycle process of resolution/racemization was described. In the process, the desired (R)-1 was obtained by resolution with D-malic acid in 95% EtOH. Meanwhile, the undesired (S)-1 could be racemized in the presence of potassium hydroxide in DMSO.