Research output: Contribution to journal › Article › peer-review
Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants : Evidence for Different Active Species and Epoxidation Mechanisms. / Zima, Alexandra M.; Lyakin, Oleg Y.; Ottenbacher, Roman V. et al.
In: ACS Catalysis, Vol. 7, No. 1, 06.01.2017, p. 60-69.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants
T2 - Evidence for Different Active Species and Epoxidation Mechanisms
AU - Zima, Alexandra M.
AU - Lyakin, Oleg Y.
AU - Ottenbacher, Roman V.
AU - Bryliakov, Konstantin P.
AU - Talsi, Evgenii P.
N1 - Publisher Copyright: © 2016 American Chemical Society.
PY - 2017/1/6
Y1 - 2017/1/6
N2 - Iron complexes with chiral bipyrrolidine-derived aminopyridine (PDP) ligands are among the most efficient Fe-based bioinspired catalysts for regio- and stereoselective oxidation of C-H and C=C moieties with hydrogen peroxide. Besides hydrogen peroxide, other oxidants (peroxycarboxylic acids and organic hydroperoxides) can be effectively used. In this work, we have examined the mechanistic landscape of the Fe(PDP) catalyst family with various oxidants: H2O2, organic hydroperoxides, and peracids. The combined EPR spectroscopic, enantioselectivity, Hammett, Z-stilbene epoxidation stereoselectivity, and 18O-labeling data witness that the same oxoiron complexes [(L)FeV=O(OC(O)R)]2+ are the actual epoxidizing species in both the catalyst systems (L)Fe/H2O2/carboxylic acid and (L)Fe/AlkylOOH/carboxylic acid. On the contrary, in the systems (L)Fe/R2C(O)OOH (R2 = CH3 or 3-Cl-C6H4), in the presence or in the absence of carboxylic acid, the epoxidation is predominantly conducted by the acylperoxo-iron(III) intermediates [(L)FeIII(OOC(O)R2)]2+, in a concerted fashion.
AB - Iron complexes with chiral bipyrrolidine-derived aminopyridine (PDP) ligands are among the most efficient Fe-based bioinspired catalysts for regio- and stereoselective oxidation of C-H and C=C moieties with hydrogen peroxide. Besides hydrogen peroxide, other oxidants (peroxycarboxylic acids and organic hydroperoxides) can be effectively used. In this work, we have examined the mechanistic landscape of the Fe(PDP) catalyst family with various oxidants: H2O2, organic hydroperoxides, and peracids. The combined EPR spectroscopic, enantioselectivity, Hammett, Z-stilbene epoxidation stereoselectivity, and 18O-labeling data witness that the same oxoiron complexes [(L)FeV=O(OC(O)R)]2+ are the actual epoxidizing species in both the catalyst systems (L)Fe/H2O2/carboxylic acid and (L)Fe/AlkylOOH/carboxylic acid. On the contrary, in the systems (L)Fe/R2C(O)OOH (R2 = CH3 or 3-Cl-C6H4), in the presence or in the absence of carboxylic acid, the epoxidation is predominantly conducted by the acylperoxo-iron(III) intermediates [(L)FeIII(OOC(O)R2)]2+, in a concerted fashion.
KW - asymmetric epoxidation
KW - bioinspired catalysis
KW - enantioselectivity
KW - EPR
KW - iron
KW - mechanism
KW - NONHEME IRON
KW - OLEFIN EPOXIDATION
KW - COMPLEXES
KW - H2O2
KW - ONE-ELECTRON OXIDATION
KW - ASYMMETRIC EPOXIDATION
KW - METHYLENIC SITES
KW - C-H OXIDATION
KW - SELECTIVITY
KW - FE
UR - http://www.scopus.com/inward/record.url?scp=85019668398&partnerID=8YFLogxK
U2 - 10.1021/acscatal.6b02851
DO - 10.1021/acscatal.6b02851
M3 - Article
AN - SCOPUS:85019668398
VL - 7
SP - 60
EP - 69
JO - Topics in Catalysis
JF - Topics in Catalysis
SN - 1022-5528
IS - 1
ER -
ID: 9048784