Asymmetric Vinylogous Aza-Darzens Approach to Vinyl Aziridines

A new asymmetric approach to assemble <i>cis</i>-vinyl aziridines is reported. A reaction of strategically substituted dienolates, decorated with a γ-leaving group, with chiral sulfinimines afforded chiral vinyl aziridine products in good to excellent yields. This is the first systematic study toward the realization of a useful asymmetric vinylogous aza-Darzens reaction. The reaction is initiated by a <i>syn</i>-selective addition, affording <i>cis</i>-vinyl aziridine products after displacement of bromide. The low <i>syn</i>-diastereoselectivity is attributed to competing retro-Mannich pathways