Regiochemistry And Mechanism Of Oxidation Of
N-Benzyl-N-Alkylhydroxylamines To Nitrones
Hassan, A; Wazeer, MIM; Saeed, MT; Siddiqui, MN; Ali, SA
JOHN WILEY SONS LTD, JOURNAL OF PHYSICAL ORGANIC CHEMISTRY; pp: 443451; Vol: 13
King Fahd University of Petroleum & Minerals
http://www.kfupm.edu.sa
Summary
The oxidation of various N-(o-, m-, p-substituted benzyl)-N-alkylhydroxylamines and
their dideuteriobenzyl (PhCD2) counterparts was carried out using mercury(II) oxide
and p-benzoquinone (p-BQ) as oxidants. An overwhelming preference for the
formation of conjugated nitrones is observed in the oxidation of N-benzyl-Nisopropylhydroxylamines. Considerable intra- and intermolecular kinetic isotope
effects and negative rho values in the Hammet plots point towards a mechanistic
pathway that involves electron transfer from nitrogen to the oxidant followed by
hydrogen abstraction. The conformation of unstable (E)-nitrones, which readily
isomerize to the more stable (Z)-nitrones, is deduced from H-1 NMR data. The E = Z
isomerization was found to be a bimolecular process. Copyright (C) 2000 John Wiley
Sons, Ltd.
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Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa