title: First direct evidence for stereospecific olefin epoxidation and alkane hydroxylation by an oxoiron(IV) porphyrin complex.
abstract: We report in this study that an oxoiron(IV) porphyrin complex bearing electron-deficient porphyrin ligand, (TPFPP)FeIV=O (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion), shows reactivities similar to those found in oxoiron(IV) porphyrin pi-cation radicals. In the epoxidation of olefins by the (TPFPP)FeIV=O complex, epoxides were yielded as major products; cyclohexene oxide was the sole product formed in the epoxidation of cyclohexene, and stilbenes were stereospecifically oxidized to the corresponding epoxide products. More striking results were obtained in alkane hydroxylation reactions; the hydroxylation of adamantane afforded a high degree of selectivity for tertiary C-H bonds over secondary C-H bonds, and the hydroxylation of cis-1,2-dimethylcyclohexane yielded a tertiary alcohol product with >99% retention of stereochemistry. The latter result demonstrates that an oxoiron(IV) porphyrin complex hydroxylates alkanes with a high stereospecificity. Isotope labeling studies performed with H218O and 18O2 in the olefin epoxidation and alkane hydroxylation reactions demonstrated that oxygen atoms in oxygenated products derived from the oxoiron(IV) porphyrin complex.
authors.affiliation: Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
authors.forename: Se-Eun
authors.initials: SE
authors.lastname: Park
authors.forename: In Kyung
authors.initials: IK
authors.lastname: Lim
authors.forename: Mi Hee
authors.initials: MH
authors.lastname: Lim
authors.forename: Jongki
authors.initials: J
authors.lastname: Hong
authors.forename: Jinheung
authors.initials: J
authors.lastname: Kim