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Enantioselective, NHC-Catalyzed Annulations of Trisubstituted Enals and Cyclic N-Sulfonylimines via α,β-Unsaturated Acyl Azoliums


  • We are grateful to the ETH-Zürich for supporting this research. We thank Benedikt Wanner for a preliminary investigation and Dr. Bernd Schweizer (X-ray structure analysis) and the MS services at ETH-Zürich.


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All aboard please! A new reaction of enals and cyclic sulfonylimines, as the nucleophiles(!), is the first highly enantioselective NHC-catalyzed annulation of trisubstituted enals. The catalytically generated α,β-unsaturated acyl azolium undergoes a reaction with the enamine tautomer of the imine via an aza-Claisen rearrangement as the key C[BOND]C bond-forming step. High yields and enantioselectivities were achieved using β-, α,β-, and β,β′-substituted enals.