Amine oxidative N-dealkylation via cupric hydroperoxide Cu-OOH homolytic cleavage followed by site-specific fenton chemistry.
J Am Chem Soc
; 137(8): 2867-74, 2015 Mar 04.
Article
en En
| MEDLINE
| ID: mdl-25706825
Copper(II) hydroperoxide species are significant intermediates in processes such as fuel cells and (bio)chemical oxidations, all involving stepwise reduction of molecular oxygen. We previously reported a Cu(II)-OOH species that performs oxidative N-dealkylation on a dibenzylamino group that is appended to the 6-position of a pyridyl donor of a tripodal tetradentate ligand. To obtain insights into the mechanism of this process, reaction kinetics and products were determined employing ligand substrates with various para-substituent dibenzyl pairs (-H,-H; -H,-Cl; -H,-OMe, and -Cl,-OMe), or with partially or fully deuterated dibenzyl N-(CH2Ph)2 moieties. A series of ligand-copper(II) bis-perchlorate complexes were synthesized, characterized, and the X-ray structures of the -H,-OMe analogue were determined. The corresponding metastable Cu(II)-OOH species were generated by addition of H2O2/base in acetone at -90 °C. These convert (t1/2 ≈ 53 s) to oxidatively N-dealkylated products, producing para-substituted benzaldehydes. Based on the experimental observations and supporting DFT calculations, a reaction mechanism involving dibenzylamine H-atom abstraction or electron-transfer oxidation by the Cu(II)-OOH entity could be ruled out. It is concluded that the chemistry proceeds by rate limiting Cu-O homolytic cleavage of the Cu(II)-(OOH) species, followed by site-specific copper Fenton chemistry. As a process of broad interest in copper as well as iron oxidative (bio)chemistries, a detailed computational analysis was performed, indicating that a Cu(I)OOH species undergoes O-O homolytic cleavage to yield a hydroxyl radical and Cu(II)OH rather than heterolytic cleavage to yield water and a Cu(II)-O(â¢-) species.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Peróxidos
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Cobre
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Aminas
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Peróxido de Hidrógeno
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Hierro
Idioma:
En
Revista:
J Am Chem Soc
Año:
2015
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos