Alkenes isomerization with manganese

N- Aminoaziridines have been converted to alkenes by reaction with a variety of oxidizing agents (70JA1784). Usually, the deamination reaction is stereospecific. The oxidation of l-amino-2,3-diphenylaziridines with manganese dioxide, however, was not stereospecific. The trans compound gives entirely frans-stilbene, whereas the cfs-aziridine forms a mixture of 85% trans- and 15% c -aikene. cw-Stilbene is not isomerized to trans under the reaction conditions, and the results are explained in terms of an azamine intermediate which can isomerize through a tautomeric equilibrium. 

The mechanisms proposed for manganese-porphyrin-catalyzed epoxidation of olefins are similar in several respects to that proposed for salen systems (365, 400), and this was utilized initially to provide insight into the Mn-salen systems. In the case of porphyrins, a Mnv=0 moiety is also formed by reaction with the secondary oxidant, for example iodosyl benzene, and the olefin is then believed to approach in a side-on manner. Various intermediates have been proposed for the epoxidation of the olefin, including ones in which the alkene is polarized to give positive and radical ends, and those shown earlier for the salen systems. The concept of the metallaoxe-tane (371, 372) was employed to explain isomerization of some of the olefinic substrates during conversion to the epoxide products, but now... 

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