Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants

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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

BibTeX

@article{e8951f8391004c9d8322947331fa28db,

title = "Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants: Evidence for Different Active Species and Epoxidation Mechanisms",

abstract = "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.",

keywords = "asymmetric epoxidation, bioinspired catalysis, enantioselectivity, EPR, iron, mechanism, NONHEME IRON, OLEFIN EPOXIDATION, COMPLEXES, H2O2, ONE-ELECTRON OXIDATION, ASYMMETRIC EPOXIDATION, METHYLENIC SITES, C-H OXIDATION, SELECTIVITY, FE",

author = "Zima, {Alexandra M.} and Lyakin, {Oleg Y.} and Ottenbacher, {Roman V.} and Bryliakov, {Konstantin P.} and Talsi, {Evgenii P.}",

note = "Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2017",

month = jan,

day = "6",

doi = "10.1021/acscatal.6b02851",

language = "English",

volume = "7",

pages = "60--69",

journal = "Topics in Catalysis",

issn = "1022-5528",

publisher = "Springer Netherlands",

number = "1",

}

RIS

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.

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

Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants: Evidence for Different Active Species and Epoxidation Mechanisms

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