Iron-Catalyzed Olefin <i>cis</i>-Dihydroxylation by H<sub>2</sub>O<sub>2</sub>: Electrophilic versus Nucleophilic Mechanisms
作者:Megumi Fujita、Miquel Costas、Lawrence Que
DOI:10.1021/ja029863d
日期:2003.8.1
Previous studies have classified a series of nonheme iron catalysts for olefin cis-dihydroxylation by H2O2 into two groups. Complex 1, [(TPA)Fe(OTf)2], representative of Class A catalysts, forms a low-spin FeIII-OOH intermediate that gives rise to a high-valent FeV(=O)OH oxidant. The preference of this catalyst for electron-rich olefins demonstrates its electrophilic character. On the other hand, complex 2, [(6-Me3-TPA)Fe(OTf)2], representative of Class B catalysts, prefers instead to oxidize electron-deficient olefins, suggesting an oxidant with nucleophilic character. It is suggested that such a nucleophilic oxidant may be the high-spin FeIII-OOH intermediate derived from 2 or the FeIV(=O)(*OH) species derived therefrom.