Stereospecific Ring Opening and Cycloisomerization of Aziridines with Propargylamines: Synthesis of Functionalized Piperazines and Tetrahydropyrazines.

Stereospecific Cu-catalyzed nucleophilic ring opening of N-sulfonylaziridines with propargylamines and subsequent hydroamination afford piperazines, which leads to double-bond isomerization to furnish tetrahydropyrazines. Optically active aziridines can be cross-coupled with high enantiomeric purities (>98% ee).