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Intramolecular Oxidative O ‐Demethylation of an Oxoferryl Porphyrin Complexed with a Per‐ O ‐methylated β‐Cyclodextrin Dimer
Author(s) -
Kitagishi Hiroaki,
Kurosawa Shun,
Kano Koji
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201601097
Subject(s) - chemistry , porphyrin , dimer , cyclodextrin , medicinal chemistry , aqueous solution , demethylation , intramolecular force , cumene hydroperoxide , photochemistry , polymer chemistry , stereochemistry , catalysis , organic chemistry , biochemistry , gene expression , dna methylation , gene
The intramolecular oxidation of ROCH 3 to ROCH 2 OH, 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) (Fe III TPPS) and a per‐ O ‐methylated β‐cyclodextrin dimer having an ‐OCH 2 PyCH 2 O‐ linker (Py=pyridine‐3,5‐diyl). The O=Fe IV TPPS complex was formed by the reaction of met‐hemoCD3 with cumene hydroperoxide, and isolated by gel‐filtration chromatography. Although the isolated O=Fe IV TPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to Fe II TPPS ( t 1/2 =7.6 h). This conversion was accompanied by oxidative O ‐demethylation of an OCH 3 group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=Fe IV TPPS from ROCH 3 yields HO‐Fe III TPPS and ROCH 2 . . This was followed by radical coupling to afford Fe II TPPS and ROCH 2 OH. The hemiacetal (ROCH 2 OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two‐electron oxidation.