Issue 24, 2021

Triarylamine-based porous coordination polymers performing both hydrogen atom transfer and photoredox catalysis for regioselective α-amino C(sp3)–H arylation

Abstract

Direct functionalization of C(sp3)–H bonds in a predictable, selective and recyclable manner has become a central challenge in modern organic chemistry. Through incorporating different triarylamine-containing ligands into one coordination polymer, we present herein a heterogeneous approach to the combination of hydrogen atom transfer (HAT) and photoredox catalysis for regioselective C–H arylation of benzylamines. The different molecular sizes and coordination modes of the ligands, tricarboxytriphenylamine (H3TCA) and tris(4-(pyridinyl)phenyl)amine (NPy3), in one coordination polymer consolidate the triarylamine (Ar3N) moiety into a special structural intermediate, which enhances the chemical and thermal stability of the polymers and diminishes structural relaxation during the catalytic process. The inherent redox potentials of Ar3N moieties prohibit the in situ formed Ar3+ to earn an electron from C(sp3)–H nucleophiles, but allow the abstraction of a hydrogen atom from C(sp3)–H nucleophiles, enabling the formation of the C(sp3)˙ radical and the cross-coupling reaction to proceed at the most electron-rich sites with excellent regioselectivity. The new heterogeneous photoredox HAT approach skips several interactions between transient species during the typical synergistic SET/HAT cycles, demonstrating a promising redox-economical and reagent-economical heterogeneous platform that has not been reported for α-amino C–H arylation to form benzylamine derivatives. Control experiments based on monoligand coordination polymers suggested that the mixed-ligand approach improved the photochemical and photophysical properties, providing important insight into rational design and optimization of recyclable photocatalysts for rapid access to complex bioactive molecules and late-stage functionalized pharmaceuticals.

Graphical abstract: Triarylamine-based porous coordination polymers performing both hydrogen atom transfer and photoredox catalysis for regioselective α-amino C(sp3)–H arylation

Supplementary files

Article information

Article type
Edge Article
Submitted
10 Febr. 2021
Accepted
11 Maijs 2021
First published
18 Maijs 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 8512-8520

Triarylamine-based porous coordination polymers performing both hydrogen atom transfer and photoredox catalysis for regioselective α-amino C(sp3)–H arylation

H. Li, Y. Yang, X. Jing, C. He and C. Duan, Chem. Sci., 2021, 12, 8512 DOI: 10.1039/D1SC00828E

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