Highly Enantioselective C−H Oxidation of Arylalkanes with H2O2 in the Presence of Chiral Mn-Aminopyridine Complexes

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Highly Enantioselective C−H Oxidation of Arylalkanes with H₂O₂ in the Presence of Chiral Mn-Aminopyridine Complexes. / Talsi, Evgenii P.; Samsonenko, Denis G.; Ottenbacher, Roman V. et al.

In: ChemCatChem, Vol. 9, No. 24, 20.12.2017, p. 4580-4586.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{722324e79df34ff3940e9bfb6310b508,

title = "Highly Enantioselective C−H Oxidation of Arylalkanes with H2O2 in the Presence of Chiral Mn-Aminopyridine Complexes",

abstract = "Bioinspired chiral Mn-aminopyridine complexes [(S,S)-LMnII(OTf)2] and [(R,R)-LMnII(OTf)2] (where (S,S)-L=(2S,2S)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine, and (R,R)-L=(2R,2R)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine) have been shown to efficiently catalyze the benzylic C−H oxidation of arylalkanes with hydrogen peroxide in the presence of carboxylic acid additives, affording enantiomerically enriched 1-arylalkanols and the corresponding ketones. Optically pure additive N-Boc-(L)-proline, in combination with [(R,R)-LMnII(OTf)2] complex, affords 1-arylalkanols in up to 86 % ee, which is the highest reported enantioselectivity for direct benzylic hydroxylations with H2O2 in the presence of transition-metal catalysts. Oxidative kinetic resolution only slightly contributes to the increase of the observed enantiomeric excess over the reaction course. The observed kH/kD values (3.5–3.6 for the oxidation of ethylbenzene/d10-ethylbenzene) and competitive oxidation data are consistent with either a hydrogen-atom transfer/oxygen rebound or hydride transfer/oxygen rebound asymmetric hydroxylation mechanism.",

keywords = "asymmetric catalysis, C−H hydroxylation, enzyme models, hydrogen peroxide, manganese",

author = "Talsi, {Evgenii P.} and Samsonenko, {Denis G.} and Ottenbacher, {Roman V.} and Bryliakov, {Konstantin P.}",

note = "Publisher Copyright: {\textcopyright} 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim",

year = "2017",

month = dec,

day = "20",

doi = "10.1002/cctc.201701169",

language = "English",

volume = "9",

pages = "4580--4586",

journal = "ChemCatChem",

issn = "1867-3880",

publisher = "Wiley - VCH Verlag GmbH & CO. KGaA",

number = "24",

}

RIS

TY - JOUR

T1 - Highly Enantioselective C−H Oxidation of Arylalkanes with H2O2 in the Presence of Chiral Mn-Aminopyridine Complexes

AU - Talsi, Evgenii P.

AU - Samsonenko, Denis G.

AU - Ottenbacher, Roman V.

AU - Bryliakov, Konstantin P.

PY - 2017/12/20

Y1 - 2017/12/20

N2 - Bioinspired chiral Mn-aminopyridine complexes [(S,S)-LMnII(OTf)2] and [(R,R)-LMnII(OTf)2] (where (S,S)-L=(2S,2S)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine, and (R,R)-L=(2R,2R)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine) have been shown to efficiently catalyze the benzylic C−H oxidation of arylalkanes with hydrogen peroxide in the presence of carboxylic acid additives, affording enantiomerically enriched 1-arylalkanols and the corresponding ketones. Optically pure additive N-Boc-(L)-proline, in combination with [(R,R)-LMnII(OTf)2] complex, affords 1-arylalkanols in up to 86 % ee, which is the highest reported enantioselectivity for direct benzylic hydroxylations with H2O2 in the presence of transition-metal catalysts. Oxidative kinetic resolution only slightly contributes to the increase of the observed enantiomeric excess over the reaction course. The observed kH/kD values (3.5–3.6 for the oxidation of ethylbenzene/d10-ethylbenzene) and competitive oxidation data are consistent with either a hydrogen-atom transfer/oxygen rebound or hydride transfer/oxygen rebound asymmetric hydroxylation mechanism.

AB - Bioinspired chiral Mn-aminopyridine complexes [(S,S)-LMnII(OTf)2] and [(R,R)-LMnII(OTf)2] (where (S,S)-L=(2S,2S)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine, and (R,R)-L=(2R,2R)-1,1-bis((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methyl)-2,2-bipyrrolidine) have been shown to efficiently catalyze the benzylic C−H oxidation of arylalkanes with hydrogen peroxide in the presence of carboxylic acid additives, affording enantiomerically enriched 1-arylalkanols and the corresponding ketones. Optically pure additive N-Boc-(L)-proline, in combination with [(R,R)-LMnII(OTf)2] complex, affords 1-arylalkanols in up to 86 % ee, which is the highest reported enantioselectivity for direct benzylic hydroxylations with H2O2 in the presence of transition-metal catalysts. Oxidative kinetic resolution only slightly contributes to the increase of the observed enantiomeric excess over the reaction course. The observed kH/kD values (3.5–3.6 for the oxidation of ethylbenzene/d10-ethylbenzene) and competitive oxidation data are consistent with either a hydrogen-atom transfer/oxygen rebound or hydride transfer/oxygen rebound asymmetric hydroxylation mechanism.

KW - asymmetric catalysis

KW - C−H hydroxylation

KW - enzyme models

KW - hydrogen peroxide

KW - manganese

UR - http://www.scopus.com/inward/record.url?scp=85029396833&partnerID=8YFLogxK

U2 - 10.1002/cctc.201701169

DO - 10.1002/cctc.201701169

M3 - Article

AN - SCOPUS:85029396833

VL - 9

SP - 4580

EP - 4586

JO - ChemCatChem

JF - ChemCatChem

SN - 1867-3880

IS - 24

ER -

ID: 9055897