# Imine-Oxazoline (ImOx): A C 1‑Symmetric N,N‑Bidentate Ligand for Asymmetric Catalysis

## TL;DR

This paper introduces a new chiral ligand, ImOx, designed to improve asymmetric catalysis by enhancing enantioselectivity and enabling new reaction pathways.

## Contribution

The novel ImOx ligand combines features of α-diimine and pyridine oxazoline ligands with tunable steric effects for asymmetric catalysis.

## Key findings

- ImOx improves enantioselectivity in palladium-catalyzed conjugate addition reactions.
- The steric bulk of ImOx necessitates a cationic pathway for alkene insertion.
- ImOx shows stronger trans-influence and versatile redox activity compared to PyOx.

## Abstract

Asymmetric catalysis relies on the design of chiral ligands,
but
the variety of nitrogen-based ligands remains limited. To address
this gap, we have developed a class of C
1-symmetric N,N-bidentate ligands,
imine-oxazoline (ImOx), derived from amino acids through a four-step
synthesis. ImOx features an imine moiety conjugated with a chiral
oxazoline ring as a hybrid of α-diimine (ADI) and pyridine oxazoline
(PyOx) ligands. Its low symmetry allows for independent optimization
at both coordination sites. ImOx improves the enantioselectivity of
palladium-catalyzed conjugate addition reactions, demonstrating a
strong correlation between ee and the steric effects on both the imine
and oxazoline sites. Studies on well-defined organopalladium intermediates
reveal that the steric bulk of ImOx necessitates a cationic pathway
to promote alkene insertion. Structural characterization of ImOx suggests
a stronger trans-influence compared to PyOx. Moreover,
ImOx demonstrates versatile redox activity, promoting the reduction
of nickel complexes and stabilizing nickel radical complexes. We anticipate
that ImOx will expand the toolkit of chiral N-ligands for asymmetric
catalysis.