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

The controlled functionalization of a single fluorine in a CF 3 group is difficult and rare. Photochemical C-F bond functionalization of the sp 3 -C-H bond in trifluorotoluene, PhCF 3 , is achieved using catalysts made from earth-abundant lanthanides, (Cp Me4 ) 2 Ln(2- O -3,5- t Bu 2 -C 6 H 2 )(1-C{...

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Veröffentlicht in:Chemical science (Cambridge) 2022-12, Vol.13 (47), p.149-141
Hauptverfasser: Kynman, Amy E, Elghanayan, Luca K, Desnoyer, Addison N, Yang, Yan, Sévery, Laurent, Di Giuseppe, Andrea, Tilley, T. Don, Maron, Laurent, Arnold, Polly L
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Sprache:eng
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Zusammenfassung:The controlled functionalization of a single fluorine in a CF 3 group is difficult and rare. Photochemical C-F bond functionalization of the sp 3 -C-H bond in trifluorotoluene, PhCF 3 , is achieved using catalysts made from earth-abundant lanthanides, (Cp Me4 ) 2 Ln(2- O -3,5- t Bu 2 -C 6 H 2 )(1-C{N(CH) 2 N( i Pr)}) (Ln = La, Ce, Nd and Sm, Cp Me4 = C 5 Me 4 H). The Ce complex is the most effective at mediating hydrodefluorination and defluoroalkylative coupling of PhCF 3 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. The controlled functionalization of a single fluorine in a CF 3 group is difficult and rare. Photochemical C-F bond functionalization is achieved using catalysts made from a range of earth-abundant lanthanides by using a ligand that enables M-L cooperativity.
ISSN:2041-6520
2041-6539
DOI:10.1039/d2sc04192h