Intramolecular Oxidative O-Demethylation of an Oxoferryl Porphyrin Complexed with a Per-O-methylated β-Cyclodextrin Dimer.
The intramolecular oxidation of ROCH3to ROCH2OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met-hemoCD3) with cumene hydroperoxide in aqueous solution. Met-hemoCD3 is composed of meso-tetrakis(4-sulfonatophenyl)porphinatoiron(III) (FeIIITPPS) and a per-O-methylated β-cyclodextrin dimer having an -OCH2PyCH2O- linker (Py=pyridine-3,5-diyl). The O=FeIVTPPS complex was formed by the reaction of met-hemoCD3 with cumene hydroperoxide, and isolated by gel-filtration chromatography. Although the isolated O=FeIVTPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to FeIITPPS (t1/2=7.6 h). This conversion was accompanied by oxidative O-demethylation of an OCH3group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=FeIVTPPS from ROCH3yields HO-FeIIITPPS and ROCH2.. This was followed by radical coupling to afford FeIITPPS and ROCH2OH. The hemiacetal (ROCH2OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two-electron oxidation.
Department of Molecular, Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0321, Japan.
Hiroaki
H
Kitagishi
Department of Molecular, Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0321, Japan.
Shun
S
Kurosawa
Department of Molecular, Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0321, Japan.
Koji
K
Kano
D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D000073398:Demethylation; D019281:Dimerization; D005290:Ferric Compounds / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry*
D056831:Coordination Complexes; D005290:Ferric Compounds; D011166:Porphyrins; D011725:Pyridines; D047392:beta-Cyclodextrins; D014867:Water; D006418:Heme; C031215:betadex; C023666:pyridine
bioinorganic chemistry; heme proteins; peroxides; porphyrinoids; supramolecular chemisty