I have found an even better procedure which is suitable for aziridines:
Organic Letters 2009, pages 503-506
The procedure is as follows (very simple): dissolve 1equiv. of the tosylamide THF. Add Water (18equiv.) and pyrrolidine (12equiv.). Then add samarium diiodide (SmI2, 6equiv.) and stir at room temperature. Reactions are finished within SECONDS!