Peroxomolybdenum complexes

The development of transition metal mediated asymmetric epoxidation started from the dioxomolybdcnum-/V-cthylcphcdrinc complex,4 progressed to a peroxomolybdenum complex,5 then vanadium complexes substituted with various hydroxamic acid ligands,6 and the most successful procedure may now prove to be the tetroisopropoxyltitanium-tartrate-mediated asymmetric epoxidation of allylic alcohols. 

Peroxomolybdenum complexes have been used stoichiometrically to effect a variety of organic conversions and catalytically, usually with f-butylhydroperoxide or H202, to effect... 

W. R. Thiel, T. Priermeier, The first olefin-substituted peroxomolybdenum complex Insight into a new mechanism for the molybdenum-catalyzed epoxidation of olefins, Angew. Chem. Int. Ed. Engl. 34 (1995) 1737. 

C. Fickert, W. Kiefer, Peroxomolybdenum complexes as epoxidation catalysts in biphasic hydrogen peroxide activation Raman spectroscopic studies and density functional calculations, Chem. Eur. J. 5 (1999) 3237. 

The epoxide is further oxidized by the peroxomolybdenum complex unless a large excess of the olefin is used [17]. 

Peroxomolybdenum-Picolinate N-oxide complex (1). The complex is prepared from Na2Mo04-2H20, H202, picolinic acid N-oxide, and Bu4NOH. It is obtained... 

The epoxide is produced via the transition state 33 resembling that suggested for epoxidation by peroxomolybdenum reagents252 and by organic peroxides. The initially formed epoxide is coordinated to the metal. Complexation of the alkene in different orientations to the metal, followed by coordination to the peroxide oxygen, was suggested on the basis of frontier orbitals.297... 

The structure and decomposition of the peroxomolybdenum-olefin complex have been investigated. Further kinetic studies suggest the structure of the transition complex shown in Eq. 29. The double bond is attacked by a positively charged oxygen.labeling has demonstrated that the oxo oxygen is not affected in the reaction. A -Steroids are oxidized with surprising stereospecificity this is evidence in favor of the 1,3-dipolar mechanism. ... 

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