Tandem asymmetric aziridination/ring-opening reactions have been developed. It was found that the addition of a sulfur ylide to N-acylhydrazones promoted by a chiral silane Lewis acid leads to the highly diastereo- and enantioselective synthesis of �-chloro-a-hydrazido esters.  The addition of electron-rich arenes and ZnCl2 to the reaction mixture leads to the highly diastereo- and enantioselective one-pot synthesis of diarylalanine derivatives.  In both tandem reactions, the silane Lewis acid serves the dual function of activating the hydrazone for ylide addition and the aziridine for nucleophilic substitution.  Practical drawbacks associated with the preparation and handling of the unstable diphenylsulfur ylide employed in these reactions were overcome via in situ generation of the ylide by means of the rhodium-catalyzed reaction of Ph2S with ethyl diazoacetate.

Tandem asymmetric aza-Darzens/ring-opening reactions: Dual functionality from the silane Lewis acid

248th National Meeting (2014)

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