Benzoquinone (BQ) and O(2) are among the most common stoichiometric oxidants in Pd-catalyzed oxidation reactions. The present study provides rare insights into mechanistic differences between BQ and O(2) in their reactivity with a well-defined Pd-hydride complex, Pd(IMes)(2)(H)(O(2)CPh) (1). BQ promotes the reductive elimination of PhCO(2)H from 1 and catalyzes the formation of a Pd(II)-OOH com...

The stability of 21 amino acid conjugates of indole-3-acetic acid (IAA) toward horseradish peroxidase (HRP) was studied. The IAA conjugates of Arg, Ile, Leu, Tyr, and Val were oxidized readily by peroxidase. Those of Ala, beta-Ala, Asp, Cys, Gln, Glu, Gly, and Lys were not degraded and their recovery was above 92% after 1 hour incubation with HRP. A correlation between the stability of IAA conj...

is catalyzed by glutathione reductase (3, 4, 5). In earlier studies this reaction has been coupled with soluble dehydrogenases which utilize TPN as a coenzyme (6). Since tissue fractionation studies have shown that numerous dehydrogenases, including those associated with the oxidation of the Krebs cycle intermediates, are localized within the mitochondrion, it was of interest to determine wheth...

The oxidative metabolism of hydralazine, isoniazid, iproniazid, and phenylhydrazine has been studied using spin-trapping techniques. The oxidation of these hydrazine derivatives, catalyzed by horseradish peroxidase and prostaglandin synthetase, produces reactive free radical intermediates. Enzymatic activation of hydralazine produce the nitrogen-centered hydralazyl radical (RNHNH.); phenylhydra...

Recent studies have highlighted the ability of Cu(II) to catalyze the aerobic oxidative functionalization of C-H bonds; however, very little is known about the mechanisms of these reactions. Here, we describe the Cu(II)-catalyzed C-H methoxylation and amidation of a macrocylic arene substrate with O(2) as the stoichiometric oxidant. Kinetic and in situ spectroscopic studies demonstrate the invo...

An acceptorless dehydrogenation of heterocycles catalyzed by frustrated Lewis pairs (FLPs) was developed. Oxidation with concomitant liberation of molecular hydrogen proceeded in high to excellent yields for N-protected indolines as well as four other substrate classes. The mechanism of this unprecedented FLP-catalyzed reaction was investigated by mechanistic studies, characterization of reacti...

Copper ion catalyzed carbon-carbon bond forming reaction of N-acyliminium ions with diaryl malonates was achieved with high enantioselectivity. The key intermediates in the method were 2-methoxy-3,4-didehydropiperidines, which were easily prepared through electrochemical oxidation of 1-(p-methoxybenzoyl)piperidine in methanol followed by the conversion of the oxidation product to didehydropiper...