Dual-Ligand-Enabled Ir(III)-Catalyzed Enantioselective C–H Amidation for the Synthesis of Chiral Sulfoxides

A rational
designed Ir­(III)-catalyzed enantioselective C–H
amidation of dibenzyl sulfoxides through desymmetrization and parallel
kinetic resolution is demonstrated. An Ir­(III) complex equipped with
a t-butyl cyclopentadienyl ligand and paired with
a modified chiral proline enables the highly enantioselective sulfoxide-steered
C–H bond activation, providing an efficient and straightforward
way to construct sulfur chiral centers. A wide range of dibenzyl sulfoxides
and dioxazolones are compatible with this process, giving access to
a variety of highly functionalized sulfoxide compounds with synthetically
attractive amide substitution groups in good yields and enantioselectivities.
Moreover, the flexible derivatization of the amidated sulfoxide was
elaborated, providing various types of chiral sulfoxide scaffolds
that would be potentially useful in asymmetric catalysis as chiral
bidentate and tridentate ligands.