Oxidative using manganese porphyrin

Battioni, P., J.F. Bartoli, P. Leduc, M. Fontecave, and D. Mansuy (1987). A new and efficient biomimetic system for hydrocarbon oxidation by dioxygen using manganese porphyrins, imidazole, and zinc. J. Chem. Soc., Chem. Commun. 791-792. 

Certain robust manganese porphyrins [e.g., manganese(IH) tetra(2, 6 -dichloro-pheny])porphyrin chloride] are able to catalyze stereoselective epoxidations, when applied in the presence of imidazole324-327 or other heterocyclic nitrogen bases.326 NaI04324 or even H202325-327 can be used as oxidant. 

The results from the publications mentioned are of interest because they can help in the creation of effective catalytic systems containing porphyrins, which combine functions typical of multienzyme systems. The task in hand is the possible synthesis of bifunctional catalysts based on metalloporphyrin systems, when with the help of manganese porphyrins, for example, or SOD mimic, hydrogen peroxide is accumulated in the system. Afterwards, the accumulated hydrogen peroxide is used in oxidation reactions of various substrates with iron porphyrin components of the catalyst. 

Tabushi and Koga reported the use of manganese porphyrins to catalyze the 02-oxidation of cyclohexene to cyclohexanol and cyclohexene-ol in the presence of borohydride these workers suggest that an equilibrium such as depicted in Reaction 32 is involved in non free-radical pathways (112). 

In a reaction modeled on the use of cytodirtxne P-450 to catalyze oxidations with iodosylbenzene, iron or manganese porphyrins have been used to catalyze aziridinations with iodinanes (Scheme 22). In this early report cis- or rranr-stilbene each gave the rrans-aziridine, but stereoselectivity has since been achieved for the sulfonylaziridines (Section 3.5.2.6). 

As stated previously, the silver(III) state is stabilized by the electron-rich nature of the ligand in addition to the cavity size contribution. The silver(III) center may easily obtain an electron from the ligand to form a ligand radical, which satisfies the metal ion s high electrophilicity. This finding may explain why in some silver(lll) complexes the silver(II) and (III) states can switch reversibly. Whether this property of silver can be utilized in oxidation catalysis the way iron and manganese porphyrin systems were used still has to be seen (27-30). 

The epoxidation of alkenes by sodium hypochlorite in the presence of manganese porphyrins under phase-transfer conditions has been thoroughly studied. Kinetic studies of this reaction revealed a Michaelis-Menten rate equation. As in Scheme 12, the active oxidant is thought to be a high-valent manganese( V)-oxo-porphyrin complex which reversibly interacts with the alkene to form a metal oxo-alkene intermediate which decomposes in the rate determining step to the epoxide and the reduced Mn porphyrin. Shape selective epoxidation is achieved when the sterically hindered complex Mn(TMP)Cl is used as the catalyst in the hypochlorite oxidation. ... 

Poly(ethylene glycol)-supported manganese porphyrins were tested in the epoxidation of cyclooctene, 1-dodecene, cyclohexene, styrene, and indene with PhIO or H2O2 in the presence of N-alkylimidazoles as axial ligands [51]. The polymers were soluble in the reaction mixtures and could be precipitated and reused. Epoxide yields from 80 to 100%, except for 1-dodecene (38% yield), were obtained using PhIO as oxidant. 

A remarkable approach was reported in 2004 by Simormeaux and coworkers [53]. Manganese complexes of spirobifluorenyl-substituted porphyrins were elec-tropolymerized by anodic oxidation and the resulting poly(9,9 -spirobifluorene manganese porphyrin) films were shown to be efficient epoxidation catalysts in the presence of imidazole. The polymers were tested in the epoxidation of cyclooctene and styrene using PhIO or PhI(OAc)2 as oxidants. Epoxide yield reached 95% in the case of cyclooctene and 77% in the case of styrene. The electrosynthesized polymers could be recovered by filtration and reused up to eight times without loss of activity and selectivity. 

---