Issue 47, 2022

Controlled monodefluorination and alkylation of C(sp3)–F bonds by lanthanide photocatalysts: importance of metal–ligand cooperativity

Abstract

The controlled functionalization of a single fluorine in a CF3 group is difficult and rare. Photochemical C–F bond functionalization of the sp3-C–H bond in trifluorotoluene, PhCF3, is achieved using catalysts made from earth-abundant lanthanides, (CpMe4)2Ln(2-O-3,5-tBu2-C6H2)(1-C{N(CH)2N(iPr)}) (Ln = La, Ce, Nd and Sm, CpMe4 = C5Me4H). The Ce complex is the most effective at mediating hydrodefluorination and defluoroalkylative coupling of PhCF3 with alkenes; addition of magnesium dialkyls enables catalytic C–F bond cleavage and C–C bond formation by all the complexes. Mechanistic experiments confirm the essential role of the Lewis acidic metal and support an inner-sphere mechanism of C–F activation. Computational studies agree that coordination of the C–F substrate is essential for C–F bond cleavage. The unexpected catalytic activity for all members is made possible by the light-absorbing ability of the redox non-innocent ligands. The results described herein underscore the importance of metal–ligand cooperativity, specifically the synergy between the metal and ligand in both light absorption and redox reactivity, in organometallic photocatalysis.

Graphical abstract: Controlled monodefluorination and alkylation of C(sp3)–F bonds by lanthanide photocatalysts: importance of metal–ligand cooperativity

Supplementary files

Article information

Article type
Edge Article
Submitted
28 Jul 2022
Accepted
05 Nov 2022
First published
08 Nov 2022
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., 2022,13, 14090-14100

Controlled monodefluorination and alkylation of C(sp3)–F bonds by lanthanide photocatalysts: importance of metal–ligand cooperativity

A. E. Kynman, L. K. Elghanayan, A. N. Desnoyer, Y. Yang, L. Sévery, A. Di Giuseppe, T. D. Tilley, L. Maron and P. L. Arnold, Chem. Sci., 2022, 13, 14090 DOI: 10.1039/D2SC04192H

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