Enantioselective Benzylic Hydroxylation of Arylalkanes with H2O2 in Fluorinated Alcohols in the Presence of Chiral Mn Aminopyridine Complexes Full article
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ChemCatChem
ISSN: 1867-3880 , E-ISSN: 1867-3899 |
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| Output data | Year: 2018, Volume: 10, Number: 22, Pages: 5323-5330 Pages count : 9 DOI: 10.1002/cctc.201801476 | ||||||
| Tags | Asymmetric catalysis; C−H hydroxylation; enzyme models; hydrogen-bond donor; hydrogen peroxide; manganese | ||||||
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Funding (1)
| 1 | Federal Agency for Scientific Organizations | 0303-2016-0005 |
Abstract:
A series of chiral bioinspired Mn‐aminopyridine complexes of the type [L*MnII(OTf)2] (where L* is 2,2′‐bipyrrolidine derived ligand, bearing trifluoroalkoxy and alkyl substituents) have been tested as catalysts in benzylic C−H hydroxylation of arylalkanes with H2O2 in fluorinated ethanols media. In 2,2,2‐trifuoroethanol, the yield of the target ethylbenzene oxidation product, chiral 1‐phenylethanol, reaches 45 %, which is much better than in the common solvent CH3CN (5‐6 %). The selectivity for 1‐phenylethanol formation increases in the following order: CH3CN<2‐fluoroethanol<2,2‐difluoroethanol<2,2,2‐trifuoroethanol, while 2,2‐difluoroethanol ensures the highest asymmetric induction in this series, affording chiral benzylic alcohols with up to 89 % ee. In trifluoroethanol, the observed primary kH/kD value of 2.3 has been measured for the oxidation of 1‐phenylethanol/α‐D‐1‐phenylethanol, which is similar to that in CH3CN (2.2). At the same time, depending on the solvent, CH3CN or 2,2,2‐trifuoroethanol, the oxidations of 1‐phenylethanol demonstrates drastically different linear free‐energy relationships; possible effect of the hydrogen‐bond donor (HBD) nature of CF3CH2OH is discussed in this context. Noticeably, it has been shown that by switching the absolute chirality ((S,S)− or (R,R)−) of the catalyst, the oxidation of complex substrate of natural origin, estrone acetate, can be diverted to predominant formation of either the tertiary C9‐alcohol or of the C6‐ketone, respectively.
Cite:
Ottenbacher R.V.
, Talsi E.P.
, Rybalova T.V.
, Bryliakov K.P.
Enantioselective Benzylic Hydroxylation of Arylalkanes with H2O2 in Fluorinated Alcohols in the Presence of Chiral Mn Aminopyridine Complexes
ChemCatChem. 2018. V.10. N22. P.5323-5330. DOI: 10.1002/cctc.201801476 WOS Scopus РИНЦ AN OpenAlex
Enantioselective Benzylic Hydroxylation of Arylalkanes with H2O2 in Fluorinated Alcohols in the Presence of Chiral Mn Aminopyridine Complexes
ChemCatChem. 2018. V.10. N22. P.5323-5330. DOI: 10.1002/cctc.201801476 WOS Scopus РИНЦ AN OpenAlex
Dates:
| Submitted: | Sep 7, 2018 |
| Accepted: | Oct 2, 2018 |
| Published online: | Nov 5, 2018 |
| Published print: | Nov 22, 2018 |
Identifiers:
| Web of science: | WOS:000451444000027 |
| Scopus: | 2-s2.0-85056107536 |
| Elibrary: | 38669445 |
| Chemical Abstracts: | 2018:2109781 |
| OpenAlex: | W2894655722 |