5411-56-3Relevant articles and documents
Catalytic applications of magnetic nanoparticles functionalized using iridium N-heterocyclic carbene complexes
Iglesias, Diego,Sabater, Sara,Azua, Arturo,Mata, Jose A.
, p. 6437 - 6444 (2015)
A synthetic modular methodology allows the preparation of catalytic materials based on magnetic nanoparticles with iridium N-heterocyclic carbene (NHC) complexes. Imidazolium salts containing a ketone/aldehyde as a pendant functional group are the key species prepared. The condensation reaction of the Cp?IrNHC-CHO compound with magnetic nanoparticles containing amine groups on the surface yields the covalent anchoring of the iridium complex to the surface of the magnetite. The catalytic properties have been evaluated in transfer hydrogenation. The iridium complexes and the material are active in the reduction of ketones using isopropanol as the solvent and hydrogen donor. The catalytic results reveal that the catalytic activity of the material and the molecular complex are equivalent. We have not observed any change in activity due to the support. The recyclability properties of the magnetic material have been evaluated. The results show that the catalyst activity is maintained for two runs. This work describes a simple methodology for anchoring molecular complexes on the surface of magnetic nanoparticles.
Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
, (2022/01/04)
Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
Chromoselective Photocatalysis Enables Stereocomplementary Biocatalytic Pathways**
Schmermund, Luca,Reischauer, Susanne,Bierbaumer, Sarah,Winkler, Christoph K.,Diaz-Rodriguez, Alba,Edwards, Lee J.,Kara, Selin,Mielke, Tamara,Cartwright, Jared,Grogan, Gideon,Pieber, Bartholom?us,Kroutil, Wolfgang
supporting information, p. 6965 - 6969 (2021/03/03)
Controlling the selectivity of a chemical reaction with external stimuli is common in thermal processes, but rare in visible-light photocatalysis. Here we show that the redox potential of a carbon nitride photocatalyst (CN-OA-m) can be tuned by changing the irradiation wavelength to generate electron holes with different oxidation potentials. This tuning was the key to realizing photo-chemo-enzymatic cascades that give either the (S)- or the (R)-enantiomer of phenylethanol. In combination with an unspecific peroxygenase from Agrocybe aegerita, green light irradiation of CN-OA-m led to the enantioselective hydroxylation of ethylbenzene to (R)-1-phenylethanol (99 % ee). In contrast, blue light irradiation triggered the photocatalytic oxidation of ethylbenzene to acetophenone, which in turn was enantioselectively reduced with an alcohol dehydrogenase from Rhodococcus ruber to form (S)-1-phenylethanol (93 % ee).