Catalytic H2O2 oxidation procedure

In the noble metal-catalyzed oxidations described above vicinal diol cleavage is sometimes observed as a side-reaction but never as a main reaction. Oxidative diol cleavage usually involves stoichiometric oxidants such as periodate (Malaprade oxidation) and there is a great need for catalytic procedures employing inexpensive, clean oxidants such as O2 or H2O2. 

A novel procedure for the oxidative cleavage of indole carbon double bonds in the presence of H2O2 using plant cell cultures, as a catalytic system, led to benzazonine diones 297 (Scheme 54) <2004TL8061>. 177-Benzo[ ][l,4]diazonines 298 were obtained in a highly substituted form and in high yields by ozonolysis of 1,2,3,4-tctrahydro-9//-pyrido[3,4- indole derivatives 296 (X = NAc) <2000JME3518>. 

A convenient procedure may be based on the catalytic action in the system T1+ + HgOg and applied to the detection of MoOs, WO3 and V2O5 even in the presence of other oxides. It is essential to use ammoniacal conditions in this activation because H2O2 alone will precipitate brown TIO(OH) in caustic alkaU solution. 

Tse, M., Dobler, C., Bhor, S., et al (2004). Development of a Ruthenium-Catalyzed Asymmetric Epoxidation Procedure with Hydrogen Peroxide as the Oxidant, Angew. Chem. Int. Ed., 43, pp. 5255-5260 Tse, M., Bhor, S., Klawonn, M., et al, (2006). Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2. Part 11 catalytic Activities and Mechanism, Chem. Eur.J., 12, pp. 1875-1888. 

Aerobic and peroxidative oxidations of alcohols, in particular of benzylic alcohols, are typical model reactions due to their importance and generality inexpensive O2, H2O2 or tejt-butyl hydroperoxide (TBHP) oxidants, and simple procedures are usually involved. In this section, an overview of some interesting catalytic systems, which were lately introduced into the field of alcohol oxidation, is presented. This concerns mainly homogeneous systems, since recent advances on heterogeneous catalysts are included in Section 8. Moreover, a glance at new substrates and oxidants which could successfully be used in a near future and make a difference in terms of efficiency, selectivity, economy and/or sustainability of the processes, is also presented. 

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