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Ligand Oxidation Activates a Ruthenium(II) Precatalyst for C-H Hydroxylation.
- Source :
-
Journal of the American Chemical Society [J Am Chem Soc] 2024 Aug 21; Vol. 146 (33), pp. 23067-23074. Date of Electronic Publication: 2024 Aug 12. - Publication Year :
- 2024
-
Abstract
- A new class of Ru-sulfonamidate precatalysts for sp <superscript>3</superscript> C-H hydroxylation is described along with a versatile process for assembling unique heteroleptic Ru(II) complexes. The latter has enabled structure-performance studies to identify an optimal precatalyst, 2h , bearing one 4,4'-di- tert -butylbipyridine (dtbpy) and one pyridylsulfonamidate ligand. Single-crystal X-ray analysis confirmed the structure and stereochemistry of this adduct. Catalytic hydroxylation reactions are conveniently performed in an aqueous, biphasic solvent mixture with 1 mol % 2h and ceric ammonium nitrate as the terminal oxidant and deliver oxidized products in yields ranging from 37 to 90%. A comparative mechanistic investigation of 2h against a related homoleptic precatalyst, [Ru(dtbpy) <subscript>2</subscript> (MeCN) <subscript>2</subscript> ](OTf) <subscript>2</subscript> , convincingly establishes that the former generates one or more surprisingly long-lived active species under the reaction conditions, thus accounting for the high turnover numbers. Structure-performance, kinetics, mass spectrometric, and electrochemical analyses reveal that ligand oxidation is a prerequisite for catalyst activation. Our findings sharply contrast a large body of prior art showing that ligand oxidation is detrimental to catalyst function. We expect these results to stimulate future innovations in C-H oxidation research.
Details
- Language :
- English
- ISSN :
- 1520-5126
- Volume :
- 146
- Issue :
- 33
- Database :
- MEDLINE
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 39134028
- Full Text :
- https://doi.org/10.1021/jacs.4c04117