Catalytic oxygenation of organic substrates: Toward greener ways for incorporating oxygen

The incorporation of oxygen to organic substrates has been matter of great interest in chemistry. With the growing concern for the environment, this reaction has also been subject of investigation to bring out more environmentally friendly systems. The use of hydrogen peroxide or nitrous oxide as oxidants can become an alternative to more pollutant compounds and, even though these generate by-products, the latter are considered benign. Besides that, the transformation of environmentally harmful chemicals, such as N2O, into more benign products, is desirable. This review summarizes the advances from the past decade in the field of homogeneous oxygenation using transition metal catalysts and H2O2 or N2O as oxygen sources. For H2O2, emphasis has been done in the contributions on oxidative functionalization of alkanes using metals from the groups 7 and 8, and the oxidation of organosulfur compounds, focused on the systems with potential to perform oxidative desulfurization and those that mediate sulfoxidation. For N2O, the activation of the oxidant at metal centers is discussed, even if the complexes do not engage yet in catalytic systems, since the coordination compounds obtained could potentially perform as catalysts in several oxygen atom transfer reactions. The main activation pathways of the oxidants, as well as the efficiency and selectivity of the systems is discussed. (C) 2015 Elsevier B.V. All rights reserved.