Studies of Alkene Oxidation Reactions by Metal-Oxo Compounds

Technische TJniversitat Milnchen, Anorganisch-chemisches Institut, Lichtenbergstrafie 4, D-85747 Garching bei Munchen, Germany 

Stoichiometric and catalytic transition-metal oxidation reactions are of great interest, because of their important role in industrial and synthetic processes. The oxidation of alkenes is one of the fundamental reactions in chemistry.1 Most bulk organic products contain functional groups, which are produced in the chemical industry by direct oxidation of the hydrocarbon feedstock. Usually these reactions employ catalysts to improve the yields, to reduce the necessary activation energy and render the reaction more economic. The synthesis of almost every product in chemical industry nowadays employs at least one catalytic step. The oxidation products of alkenes, epoxides and glycols, may be transformed into a variety of functional groups and therefore the selective and catalytic oxidation of alkenes is an industrially important process. 

Several oxidants (Fig. 1) are used as the oxygen source. Examples are bleach (NaOCl), hydrogen peroxide (H202), organic peroxides like dimethyldioxyrane (DMD) or ferf-butyl hydroperoxide (TBHP), peracids like m-chloroperbenzoic acid (mCPBA) or potassium monoperoxysulfate (KHSO5). 

ADVANCES IN PHYSICAL ORGANIC CHEMISTRY VOLUME 38 ISSN 0065-3160 DOI 10.1016/S0065-3160(03)38004-9 

But for economic reasons oxygen or even air is the most attractive oxidant for the chemical industry. 

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Computational studies of alkene oxidation reactions by metal-oxo compounds, 38, 131 Computational studies on the mechanism of orotidine monophosphate decarboxylase,... 

Computational studies of alkene oxidation reactions by metal-oxo compounds,... 

The reaction mechanisms of these transition metal mediated oxidations have been the subject of several computational studies, especially in the case of osmium tetraoxide [7-10], where the controversy about the mechanism of the oxidation reaction with olefins could not be solved experimentally [11-20]. Based on the early proposal of Sharpless [12], that metallaoxetanes should be involved in alkene oxidation reactions of metal-oxo compounds like Cr02Cl2, 0s04 and Mn04" the question arose whether the reaction proceeds via a concerted [3+2] route as originally proposed by Criegee [11] or via a stepwise [2+2] process with a metallaoxetane intermediate [12] (Figure 2). 

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