Chinese scholars have made progress in the construction of light/cobalt synergistic catalytic axial chirality

Visible light-induced cobalt-induced asymmetric radical coupling constructs axial chiral compounds

With the support of the National Natural Science Foundation of China (approval number: 91956201, 21820102003, 21822103), Xiao Wenjing and Lu Liangqiu's team of Central China Normal University made progress
in the construction of light/cobalt collaborative catalytic axifold chirality 。 The results were published on September 15, 2022 in the journal "Construction of axial chirality via asymmetric radical trapping by cobalt under visible light" in Nature? Nature Catalysis
.
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Axial chiral skeletons are common structural units of natural products, chiral drugs and materials, and are also an important part
of chiral reagents, ligands and catalysts in asymmetric synthesis.
Therefore, the development of efficient and highly selective axial chiral construction methods has always been an important research content
of chiral science.
In recent years, the use of visible light to produce highly active free radicals under mild conditions to achieve green, efficient synthesis of central chiral compounds has been reported
.
However, asymmetric synthesis of related axonal chiral skeletons has rarely been reported
.

Compared with the asymmetric radical coupling reaction catalyzed by metal nickel and copper, cobalt activity is high, the non-chiral background reaction is strong, and the reaction selectivity control is difficult
.
Xiao Wenjing and Lu Liangqiu's research team envisioned that the octahedral structure formed by complexing with ligands by using the multicoordination characteristics of cobalt is conducive to asymmetric induction; Combined with the photocatalytic process, the radical intermediate is generated by the photocatalyst in the excited state and the valence state of the metal cobalt is regulated, and it is expected to achieve an asymmetric cobalt-catalyzed radical coupling reaction and construct an axial chiral compound
.
By selecting suitable chiral multi-toothed ligands to inhibit the achiral background reaction, the team successfully developed a visible light-induced asymmetric cobalt-catalyzed radical coupling reaction, realized the dynamic kinetic asymmetric conversion of biheteroaryl compounds, and synthesized axonal chiral bis-aryl compounds (Figure).

The reaction functional group has excellent tolerance, good substrate applicability, and high
enantiomeric selectivity.
In addition, the team also studied the optical properties of axial chiral bi-heteroaryl products, and found a class of axial chiral skeletons
with good circular polarization luminescence properties.

This study not only provides a new idea for the asymmetric radical coupling reaction catalyzed by light/cobalt collaboration, but also provides a new method
for the preparation of axial chiral heteroaryl skeleton and related functional materials.