5062-38-4Relevant academic research and scientific papers
To Rebound or...Rebound? Evidence for the "alternative Rebound" mechanism in Ca'H Oxidations by the systems nonheme Mn Complex/H2O2/carboxylic acid
Ottenbacher, Roman V.,Bryliakova, Anna A.,Shashkov, Mikhail V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 5517 - 5524 (2021/05/31)
In this work, it has been shown that aliphatic Ca'H oxidations by bioinspired catalyst systems Mn aminopyridine complex/H2O2/carboxylic acid in acetonitrile afford predominantly a mixture of the corresponding alcohol and the ester. The alcohol/ester ratio is higher for catalysts bearing electron-donating groups at the aminopyridine core. Isotopic labeling studies witness that the oxygen atom of the alcohol originates from the H2O2molecule, while the ester oxygen comes exclusively from the acid. Oxidation of ethylbenzene in the presence of acetic acid affords enantiomerically enriched 1-phenylethanol and 1-phenyl acetate, with close enantioselectivities and the same sign of absolute chirality. Experimental data and density functional theory calculations provide evidence in favor of the rate-limiting benzylic H atom abstraction by the high-spin (S = 1) [LMnV(O)OAc]2+active species followed by competitive OH/OC(O)R rebound. This mechanism has been unprecedented for Ca'H oxidations catalyzed by bioinspired Mn complexes. The trends governing the alcohol/ester ratios have been rationalized in terms of steric properties of the catalyst, acid, and substrate. copy; 2021 American Chemical Society.
Mechanism of Selective C-H Hydroxylation Mediated by Manganese Aminopyridine Enzyme Models
Ottenbacher, Roman V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 39 - 44 (2015/04/27)
The mechanism of selective oxidation of aliphatic C-H groups with H2O2 in the presence of aminopyridine Mn complexes, modeling the reactivities of natural oxygenases of the cytochrome P450 superfamily, has been examined. The oxygenation of C-H groups proceeds via hydrogen atom abstraction by the electrophilic metal site; the logarithm of C-H oxidation rates correlates linearly with bond dissociation energies for homolytic C-H bond cleavage. Hammett correlations and stereospecificity studies reflect the formation of a short-lived electron-deficient radical intermediate. Isotopic labeling studies confirm the incorporation of 18O from added H218O, thus providing so far lacking evidence for the oxomanganese(V)-mediated oxidation mechanism. (Figure Presented).
Oxidative Decarboxylation of Some Bicyclohept-3-ene-1-carboxylic Acids
Galloway, Neil,Dent, Barry R.,Halton, Brian
, p. 593 - 599 (2007/10/02)
Treatment of the bicyclohept-3-ene-1-carboxylic acids (8d-f) with lead tetraacetate results in oxidative decarboxylation and formation of the 1-aryl-1-methylethyl acetates (12a-c).
