2-(2-Bromophenyl)pyrrolidine is a drug that has been studied for its effects on cyclophilins, which are involved in the regulation of cell division. The crystal structure of 2-bromopyrrolidine has been determined by x-ray crystallography and computational simulations. The distal phenyl group of the molecule binds to the active site of cyclophilin A, and this binding prevents ATP from binding, leading to inhibition of cell division. This compound also inhibits cyclophilin B and D. 2-(2-Bromophenyl)pyrrolidine is a member of the family of drugs called pyrazolopyrimidines that target cyclophilins for treatment of cancer and inflammatory diseases.