Reactive iron porphyrin derivatives related to the catalytic cycles of cytochrome P-450 and peroxidase. Studies of the mechanism of oxygen activation
作者:John T. Groves、Yoshihito. Watanabe
DOI:10.1021/ja00233a021
日期:1988.12
Mecanisme d'oxydation de [Fe(III) TMP(X)] par des peracides. TMP=tetramesitylporphyrine; X=Cl, OH
Mecanisme d'oxydation de [Fe(III) TMP(X)] par des peracides。TMP=四甲基卟啉;X=Cl,OH
Acylperoxo-Iron(III) Porphyrin Complexes: A New Entry of Potent Oxidants for the Alkene Epoxidation
作者:Kenji Machii、Yoshihito Watanabe、Isao Morishima
DOI:10.1021/ja00130a007
日期:1995.6
Competitive epoxidation of norbornylene and alpha-methylstyrene by peracids in the presence of iron porphyrins has been carried out in methylene chloride and toluene at -78 degrees C. When (TMP)Fe-III(RCO(2)) (TMP = 5,10,15,20-tetramesitylporphyrin) is used as a catalyst in methylene chloride, selectivity of norbornylene oxide over alpha-methylstyrene oxide is almost identical even though a variety of peracids are used, since O=Fe(IV)TMP pi-cation radical 2a is the common oxidant in the reactions. On the other hand, the selectivity in the epoxidations catalyzed by (TDCPP)Fe-III(X) (TDCPP: 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin is found to be dependent on the structure of peracids. The latter type of the results is also obtained for the reactions catalyzed both by (TMP)Fe-III(X) and by (TDCPP)Fe-III(X) in toluene. The dependence of the selectivity in the epoxidation on the structure of peracids is attributed to the alteration of the oxidant from 2 to peracid-Fe(III) complexes 1. The direct involvement of 1 in the epoxidation has been further confirmed by spectroscopic studies of the reactions. Under the catalytic epoxidation conditions at low temperature, the participation of 1 and 2 as the active species is controlled either by electronic structure of iron porphyrin complexes (push-pull effect) or by alteration of the solvent.