Research output: Contribution to journal › Article › peer-review
To Rebound or...Rebound? Evidence for the "alternative Rebound" mechanism in Câ'H Oxidations by the systems nonheme Mn Complex/H2O2/carboxylic acid. / Ottenbacher, Roman V.; Bryliakova, Anna A.; Shashkov, Mikhail V. et al.
In: ACS Catalysis, Vol. 11, No. 9, 07.05.2021, p. 5517-5524.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - To Rebound or...Rebound? Evidence for the "alternative Rebound" mechanism in Câ'H Oxidations by the systems nonheme Mn Complex/H2O2/carboxylic acid
AU - Ottenbacher, Roman V.
AU - Bryliakova, Anna A.
AU - Shashkov, Mikhail V.
AU - Talsi, Evgenii P.
AU - Bryliakov, Konstantin P.
N1 - Funding Information: This work was supported by the Russian Science Foundation, project 20-13-00032 (for Novosibirsk State University). A.A.B. acknowledges the access to the supercomputer facilities of the Computing Centre of Novosibirsk State University. R.V.O., M.V.S., E.P.T., and K.P.B. gratefully acknowledge the access to the facilities of the shared research center “National center of investigation of catalysts”, provided by Boreskov Institute of Catalysis. Publisher Copyright: © 2021 American Chemical Society. All rights reserved.
PY - 2021/5/7
Y1 - 2021/5/7
N2 - In this work, it has been shown that aliphatic Câ'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 Câ'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.
AB - In this work, it has been shown that aliphatic Câ'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 Câ'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.
KW - Biomimetic catalysis
KW - Câ'H activation
KW - Hydrogen peroxide
KW - Manganese
KW - Mechanism
UR - http://www.scopus.com/inward/record.url?scp=85106399321&partnerID=8YFLogxK
U2 - 10.1021/acscatal.1c00811
DO - 10.1021/acscatal.1c00811
M3 - Article
AN - SCOPUS:85106399321
VL - 11
SP - 5517
EP - 5524
JO - ACS Catalysis
JF - ACS Catalysis
SN - 2155-5435
IS - 9
ER -
ID: 34054852