Lewis Base/Copper Cooperatively Catalyzed Asymmetric α‑Amination of Esters with Diaziridinone

An enantioselective
α-amination of esters by a Lewis base/copper­(I)
cooperative catalysis strategy has been developed. The transient chiral
C1-ammonium enolate generated from pentafluorophenyl ester and nucleophilic
Lewis base is nicely compatible with the copper intermediate formed
from N,N-di-t-butyldiaziridinone
and Cu­(I) to allow for high levels of stereochemical control. The
cooperative catalytic reaction leads to a diverse set of highly enantioenriched
hydantoins in good yields with excellent enantioselectivities (90–99%
ee).