Methyltrioxorhenium synthesis

One of the most important peroxo complexes synthesized after 1983 is the rhenium species formed from methyltrioxorhenium (MTO) precursor. The synthesis of this complex is achieved in the way indicated in equation 2, by reacting hydrogen peroxide with MTO . The isolated peroxo complex 1 contains in the coordination sphere two /7 -peroxide bridges, a direct metal carbon bond and a molecule of water. The crystal structure of the peroxo rhenium derivative, however, was obtained by substitution of the water molecule with other ligands " more details on this aspect are enclosed in the structural characterization paragraph. 

Finally, a mention should be made about the one peroxo system which will become more and more dominant the organometallic oxides of rhenium(VII). Such compounds have been found to be of outstanding catalytic activity for a number of oxygen transfer reactions with hydrogen peroxide.92 The best studied complex is methyltrioxorhenium(VII) (MTO) and its congeners. Figure 2.32 illustrates its synthesis. Epoxidation, aromatic oxidation and halide oxidation with these complexes have been studied with hydrogen peroxide and shown to be remarkably efficacious. 

Methyltrioxorhenium(VII) (1), usually abbreviated to MTO, was first reported in 1979 by Beattie and Jones [2]. Due to the difficult synthesis and the low yields of 1 that could be obtained, the compound was not examined further. The break-... 

As a result, the majority of contributions to the present edition have had to be either updated or completely replaced by new articles. This applies to the sections mentioned above, but also to the rapidly growing area of enantioselective synthesis (Sections 3.3.1 and 3.2.6), the catalytic hydrogenation of sulfur- and nitrogen-containing compounds in raw oils (Section 3.2.13), the Pauson-Khand reaction (Section 3.3.7), and a number of industrially relevant topics covered under Applied Homogeneous Catalysis in Part 2. New aspects of organometallic catalysis have emerged from the chemistry of renewable resources (Section 3.3.9) and the chemistry around the multi-talented catalyst methyltrioxorhenium (Section 3.3.13). 

E. Da Palma Carreiro, G. Young-En, A. J. Burke, Approaches towards catalytic asymmetric epoxidations with methyltrioxorhenium(VII) (MTO) Synthesis and evaluation of chiral non-racemic 2-substituted pyridines, J. Mol. Cat. A.. Chem. 235, 285-292 (2005). 

Flavanones undergo a Baeyer-Villiger rearrangement to dihydro-l,5-benzodioxepin-2-ones on treatment with H2O2 and methyltrioxorhenium <01TL5401>. The synthesis of benzoxazepines from chromanones forms part of a review of the 7-membered ring compounds <01JHC1011>. 

Oxidation of Primary Amines. Goti and coworkers described a one-pot condensation/oxidation of primary amines and aldehydes (eq 46) using UHP as stoichiometric oxidant in the presence of methyltrioxorhenium as catalyst. This reaction leads to nitrones in a simple and regioselective manner. From a sustainability point of view, this one-pot synthesis is simple to perform, takes place under mild conditions, and releases water as the only byproduct. ... 

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