Hydrogen Bonding-Assisted and Nonheme Manganese-Catalyzed Remote Hydroxylation of C-H Bonds in Nitrogen-Containing Molecules.
J Am Chem Soc
; 145(9): 5456-5466, 2023 Mar 08.
Article
em En
| MEDLINE
| ID: mdl-36811463
ABSTRACT
The development of catalytic systems capable of oxygenating unactivated C-H bonds with excellent site-selectivity and functional group tolerance under mild conditions remains a challenge. Inspired by the secondary coordination sphere (SCS) hydrogen bonding in metallooxygenases, reported herein is an SCS solvent hydrogen bonding strategy that employs 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a strong hydrogen bond donor solvent to enable remote C-H hydroxylation in the presence of basic aza-heteroaromatic rings with a low loading of a readily available and inexpensive manganese complex as a catalyst and hydrogen peroxide as a terminal oxidant. We demonstrate that this strategy represents a promising compliment to the current state-of-the-art protection approaches that rely on precomplexation with strong Lewis and/or Brønsted acids. Mechanistic studies with experimental and theoretical approaches reveal the existence of a strong hydrogen bonding between the nitrogen-containing substrate and HFIP, which prevents the catalyst deactivation by nitrogen binding and deactivates the basic nitrogen atom toward oxygen atom transfer and the α-C-H bonds adjacent to the nitrogen center toward H-atom abstraction. Moreover, the hydrogen bonding exerted by HFIP has also been demonstrated not only to facilitate the O-O bond heterolytic cleavage of a putative MnIII-OOH precursor to generate MnV(O)(OC(O)CH2Br) as an active oxidant but also to affect the stability and the activity of MnV(O)(OC(O)CH2Br).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
China