Chiral N,N′-Dioxides: New Ligands and Organocatalysts for Catalytic Asymmetric Reactions

TLDR: The design of a new family of C(2)-symmetric N,N'-dioxides from readily available chiral amino acids is outlined, and the application of these chiral amine N-oxides as useful metal ligands and organocatalysts for asymmetric reactions are discussed.

Abstract: Homochiral catalysts that can effect asymmetric transformations are invaluable in the production of optically active molecules. Researchers are actively pursuing the design of new ligands and organocatalysts by exploiting concepts derived from the application of bifunctional and C2-symmetric catalysts. Many homochiral catalysts containing amines, ethers, alcohols, and phosphines as electron-pair donors have been successfully developed.Amine N-oxides are highly polar substances. Despite their pronounced capacity as electron-pair donors, N-oxides have been underutilized in asymmetric reactions; they have only made a visible impact on the field in the preceding decade. Systematic studies have instead largely focused on pyridine- or quinoline-based scaffolds in organosilicon and coordination chemistry. The application of chiral tertiary amine N-oxides has not been widely pursued because of the difficulty of controlling the chirality at the tetrahedral nitrogen of the N-oxide moiety. In this Account, we outlin...