Highly enantioselective undirected catalytic hydroxylation of benzylic CH2 groups with H2O2

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Highly enantioselective undirected catalytic hydroxylation of benzylic CH₂ groups with H₂O₂. / Ottenbacher, Roman V.; Talsi, Evgenii P.; Bryliakov, Konstantin P.

In: Journal of Catalysis, Vol. 390, 01.10.2020, p. 170-177.

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

BibTeX

@article{a258731a29314a5fafc2100c4acaff16,

title = "Highly enantioselective undirected catalytic hydroxylation of benzylic CH2 groups with H2O2",

abstract = "Chiral bis-amine-bis-pyridine Mn complexes of the type [LMnII(OTf)2] (L is 2,2ʹ-bipyrrolidine derived chiral ligand, bearing trifluoroethoxy and methyl substituents), efficiently catalyze the enantioselective hydroxylation of organic substrates at benzylic CH2 positions with H2O2. The use of β-polyfluorinated alcohols instead of CH3CN as the reaction solvents enhances the yield of chiral secondary alcohol from 5–6% up to 50–70%. The enantiomeric purity of the alcohol can be further increased (up to 97% ee) by diluting the mixture with CH3CN at late stage, which facilitates stereoconvergent oxidative kinetic resolution of the alcohol formed. Using this one-pot sequential asymmetric hydroxylation/oxidative kinetic resolution approach, the oxidation of a series of 3,4-dihydrocoumarin derivatives and 3,4-dihydroquinolinone has been realized, affording the target 4-hydroxo compounds in 40–60% isolated yield and in up to 93% ee. Besides the 4-hydroxo derivatives, formation of 3,4-epoxidation and 3,4-desaturation byproducts has been observed in some cases, thus providing evidence for unprecedented substrate-dependent hydroxylase/desaturase/epoxidase reactivity of bis-amine-bis-pyridine Mn complexes.",

keywords = "Asymmetric catalysis, C-H activation, Desaturation, Hydrogen peroxide, Manganese oxidation, OXIDATION, ASYMMETRIC HYDROXYLATION, OXYGENATION, PORPHYRIN, EPOXIDATION, HYDROGEN-PEROXIDE, DERIVATIVES, C-H HYDROXYLATION, CHIRAL IRON, ALKANES",

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

year = "2020",

month = oct,

day = "1",

doi = "10.1016/j.jcat.2020.08.005",

language = "English",

volume = "390",

pages = "170--177",

journal = "Journal of Catalysis",

issn = "0021-9517",

publisher = "Academic Press Inc.",

}

RIS

TY - JOUR

T1 - Highly enantioselective undirected catalytic hydroxylation of benzylic CH2 groups with H2O2

AU - Ottenbacher, Roman V.

AU - Talsi, Evgenii P.

AU - Bryliakov, Konstantin P.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Chiral bis-amine-bis-pyridine Mn complexes of the type [LMnII(OTf)2] (L is 2,2ʹ-bipyrrolidine derived chiral ligand, bearing trifluoroethoxy and methyl substituents), efficiently catalyze the enantioselective hydroxylation of organic substrates at benzylic CH2 positions with H2O2. The use of β-polyfluorinated alcohols instead of CH3CN as the reaction solvents enhances the yield of chiral secondary alcohol from 5–6% up to 50–70%. The enantiomeric purity of the alcohol can be further increased (up to 97% ee) by diluting the mixture with CH3CN at late stage, which facilitates stereoconvergent oxidative kinetic resolution of the alcohol formed. Using this one-pot sequential asymmetric hydroxylation/oxidative kinetic resolution approach, the oxidation of a series of 3,4-dihydrocoumarin derivatives and 3,4-dihydroquinolinone has been realized, affording the target 4-hydroxo compounds in 40–60% isolated yield and in up to 93% ee. Besides the 4-hydroxo derivatives, formation of 3,4-epoxidation and 3,4-desaturation byproducts has been observed in some cases, thus providing evidence for unprecedented substrate-dependent hydroxylase/desaturase/epoxidase reactivity of bis-amine-bis-pyridine Mn complexes.

AB - Chiral bis-amine-bis-pyridine Mn complexes of the type [LMnII(OTf)2] (L is 2,2ʹ-bipyrrolidine derived chiral ligand, bearing trifluoroethoxy and methyl substituents), efficiently catalyze the enantioselective hydroxylation of organic substrates at benzylic CH2 positions with H2O2. The use of β-polyfluorinated alcohols instead of CH3CN as the reaction solvents enhances the yield of chiral secondary alcohol from 5–6% up to 50–70%. The enantiomeric purity of the alcohol can be further increased (up to 97% ee) by diluting the mixture with CH3CN at late stage, which facilitates stereoconvergent oxidative kinetic resolution of the alcohol formed. Using this one-pot sequential asymmetric hydroxylation/oxidative kinetic resolution approach, the oxidation of a series of 3,4-dihydrocoumarin derivatives and 3,4-dihydroquinolinone has been realized, affording the target 4-hydroxo compounds in 40–60% isolated yield and in up to 93% ee. Besides the 4-hydroxo derivatives, formation of 3,4-epoxidation and 3,4-desaturation byproducts has been observed in some cases, thus providing evidence for unprecedented substrate-dependent hydroxylase/desaturase/epoxidase reactivity of bis-amine-bis-pyridine Mn complexes.

KW - Asymmetric catalysis

KW - C-H activation

KW - Desaturation

KW - Hydrogen peroxide

KW - Manganese oxidation

KW - OXIDATION

KW - ASYMMETRIC HYDROXYLATION

KW - OXYGENATION

KW - PORPHYRIN

KW - EPOXIDATION

KW - HYDROGEN-PEROXIDE

KW - DERIVATIVES

KW - C-H HYDROXYLATION

KW - CHIRAL IRON

KW - ALKANES

UR - http://www.scopus.com/inward/record.url?scp=85089818642&partnerID=8YFLogxK

U2 - 10.1016/j.jcat.2020.08.005

DO - 10.1016/j.jcat.2020.08.005

M3 - Article

AN - SCOPUS:85089818642

VL - 390

SP - 170

EP - 177

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

ER -

ID: 25285583