Shape-selective Oxidation Catalyzed by Sterically Controlled Metalloporphyrins

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New types of synthetic metalloporphyrin catalyzed epoxidation of olefins. The reaction was carried out in dichloromethane-water system by use of hypochlorite as an oxygen source. In the oxygenation of styrene catalyzed by an atropisomeric manganese porphyrin(<alpha><alpha> <alpha><alpha> isomer), the reaction took place in the preference for open site to the crowded one. Several orthosubstituted tetraphenylporphyrins were prepared:The ortho positions were substituted by nitro, fluoro or chloro groups. Their complexes showed high stability to the decomposition of catalyst. By use of these iron(III) complexes, we developed the iron porphyrin-hypochlorite system to efficient catalyst. The initial rate of the epoxidation exhibited the substrate saturation kinetics similar to the enzymatic process. From the systematic survey of epoxidation catalyzed by these metalloporphyrins, it is evident that Michaelis-Menten's parameters and and product selectivity are influenced by shape of catalysts. In addition it was indicated that the epoxidation mechanism is different between manganese and iron catalysts.