Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects.

Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Research Abstract Details 

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Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Abstract Text:

Jason Shearer,Christiana Xin Zhang,Lanying Q Hatcher,Kenneth D Karlin,

Copper-dioxygen adducts are important biological oxidants. To gain a better understanding of the underlying chemistries of such species, we report on a series of Cu2II-O2 complexes, [{CuII(MePY2)R'}2(O2)](B(C6F5)4)2 (1R') (where (MePY2)R' is a 4-pyridyl substituted bis[2-(2-(4-R'-pyridyl)ethyl]methylamine; R' = H, MeO, Me2N; Zhang, C. X.; et al. J. Am. Chem. Soc. 2003, 125, 634-635), which readily oxidize exogenous substrates. In this study, we explore the mechanism by which 1R' facilitates the oxidative N-dealkylation of para-substituted N,N-dimethylanilines (R-DMA; R = MeO, Me, H, CN). In the case of 1H, the linear free-energy correlation plot (rho = -2.1) and intramolecular deuterium kinetic isotope effect (KIEintra, using p-R-(C6H4)-N(CH3)(CD3)) profile suggest that R-DMA oxidation occurs through rate-limiting electron transfer (ET). This mechanism was further enforced by comparison of KIEintra versus the intermolecular KIE (KIEinter, using p-R-(C6H4)-N(CH3)2 versus p-R-(C6H4)-N(CD3)2). It was found that KIEinter < KIEintra, suggesting an ET process. In the case of both 1MeO and 1Me2N, the KIEintra profile and linear free-energy correlation plots (rho = -0.49 and -0.99 for 1Me2N and 1MeO with especially poor fitting for the latter) are inconclusive in distinguishing between a rate-limiting ET or hydrogen atom transfer (HAT) pathway. Comparisons of KIEinter versus KIEintra demonstrate a switch in mechanism from ET to HAT for 1Me2N and 1MeO oxidation of R-DMA as R-DMA is made less reducing. In the case of 1Me2N, MeO-DMA and Me-DMA are oxidized via a rate-limiting ET (KIEinter < KIEintra), while H-DMA and CN-DMA are oxidized through a HAT pathway (KIEinter approximately KIEintra). For 1MeO, oxidation occurs through an ET pathway for MeO-, Me-, and H-DMA (KIEinter < KIEintra), while CN-DMA is oxidized though a HAT process (KIEinter approximately KIEintra). Copper complex attributes, which may contribute to the mechanistic observations, are suggested.

Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Publishing Authors By Initials

J Shearer,CX Zhang,LQ Hatcher,KD Karlin,

For similar inorganic chemicals: elements: chalcogens: oxygen research abstracts see: inorganic chemicals: elements: chalcogens: oxygen research

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Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: Journal of the American Chemical Society

VOLUME: 125

Page Numbers: 12670-1

Journal Abbreviation: J. Am. Chem. Soc.

ISSN: 0002-7863

DAY: 22

MONTH: Oct

YEAR: 2003

Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Information

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LANGUAGE: eng

NlmUniqueID: 7503056

Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Keywords Mesh Terms:

KEYWORDS: Oxygen

MESH TERMS: chemistry

Chemical & Substance for Abstract: Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects. Information

Substance Name: Oxygen

Registry Number: 7782-44-7

Grant and Affiliation Information for Distinguishing rate-limiting electron versus H-atom transfers in Cu2O2-mediated oxidative N-dealkylations: application of inter- versus intramolecular kinetic isotope effects.

AFFILIATION: Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA. karlin@jhu.edu

Country: United States

AGENCY: United States NIGMS

GRANT: GM28962

ACRONYM: GM

MEDLINETA: J Am Chem Soc

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