Regiodivergent and Stereospecific Aziridine Opening by Copper-Catalyzed Addition of Silicon Grignard Reagents.

A stereospecific ring opening of various 2-aryl-substituted aziridines with silicon Grignard reagents under copper catalysis is reported. The regiochemical outcome is governed by the steric demand of the silicon nucleophile. The LiCl introduced with the magnesium reagent R3 SiMgX⋅2 LiCl is shown to enhance the SN 2-type displacement of the carbon-nitrogen bond by coordination to the aziridine nitrogen atom.