Asymmetric synthesis of 2-arylpiperazines.

An asymmetric synthesis of 2-arylpiperazines starting from phenacyl bromides, a variety of which are easily available, has been established. The synthesis features a CBS reduction of phenacyl bromide to provide optically enriched compounds, an SN2 reaction of 1,2,3-oxathiazolidine 2-oxides with an azide anion with invert of configuration, and construction of the piperazine ring via reduction of piperazine-2,3-diones.