Enantioselective Synthesis of ε-Lactams via Rh(I)-Catalyzed C─C Bond Activation.

ε-Lactams are important structural motifs in medicinal chemistry, but a fully enantioselective synthesis without byproduct formation represents a challenge that has attracted significant research interest. Herein, we report an atom- and step-economic synthesis of chiral ε-lactams via Rh(I)-catalyzed enantioselective C─C bond activation of aminocyclopropanes. The catalytic C─C bond activation enables a directed generation of chiral rhodacyclobutanes that circumvents β-hydride decomposition. Subsequent enantioselective cycloaddition of the alkene unit and then fragmentation generates chiral ε-lactams. A range of enantioenriched ε-lactams have been obtained with excellent regio- and enantioselectivities, which can undergo several stereospecific transformations. Theoretical calculations are performed to reveal the reaction mechanism and the origin of enantioselectivity control.