Takahiro Tezuka

Hydroxyl radical as a strong electrophilic species

In order to clarify an index which could be used as proof of the presence of hydroxyl radical, a new standard isomer distribution ratio of phenols formed from aromatic hydroxylation with [(4-bromophenyl)diazenyl](phenyl)methyl hydroperoxide 4, which is a stable source of hydroxyl radical, under a new appropriate photolysis condition in the presence or absence of benzoquinones is reported. We also demonstrated the strong electrophilic properties of hydroxyl radical in reference to earlier results of electron density calculations.

Photolysis of asym-N2O4 (ONONO2) isolated in an argon matrix at 11 K☆

Abstract An unstable isomer of dinitrogen tetroxide. ONONO 2 (asym-N 2 O 4 ), was photolyzed in an Ar matrix at 11 K at 436 and ≳ 510 nm. Asym- to sym-N 2 O 4 (O 2 NNO 2 ) isomerization was the major process at 436 nm; other products observed where NO, cis-(NO) 2 , asym-N 2 O 3 (O 2 NNO) and N 2 O 5 . Irradiation of asym-N 2 O 4 at ≳510 nm induced no reaction.

Conformationally favored CH---O intramolecular interaction and restricted rotation in sterically crowded ester

Abstract Restricted rotation of a sterically crowded ester, which has two tert -butyl groups and one isopropyl group, was studied by dynamic NMR spectroscopy. The intramolecular through-space interaction between the methine hydrogen of the isopropyl group and the carbonyl oxygen exists in the ester. Bulky alkyl substituents in close proximity cause both restricted rotation of the C(sp 3 )C(sp 3 ) single bond and CH---O intramolecular interaction.

STUDIES OF STERIC EFFECTS. SPECTROSCOPIC EVIDENCE FOR THROUGH-SPACE INTERACTION IN CH3----O IN CROWDED ALCOHOLS

Abstract Through-space interaction of the γ-methyl hydrogen with the oxygen atom in crowded tertiary aliphatic alcohols generates an abnormally low-field chemical shift in the 17 O NMR spectra. The intramolecular through-space attractive interaction or hydrogen bonding interaction between the γ-methyl hydrogen and the oxygen lone pair (CH 3 …. O) is proposed as the cause of this shift. By this interaction, the less polar CO bond is generated.

Thermal high yield aromatic arylation with α-azohydroperoxide (part 1). A novel free radical aromatic arylation reaction

Abstract Heating α-azohydroperoxide ( 1 ) (ca. 10−3 M) in benzene under reflux with bubbling inert gas for 20 – 23 hours affords biphenyls ( 2 ) in high yields (70 – 90%). A mechanism involving an induced decomposition radical chain reaction is suggested.

A novel base-catalyzed transformation of α-azobenzyl hydroperoxide into benzoic acid. A postulated oxenoid intermediate of the reaction

Abstract α-Azobenzyl hydroperoxide ( 1 gives benzoic acid, 4-bromophenylpyridines ( 2 and 3 ) in addition to benzoyldiazene ( 4 ) and benzohydrazide ( 5 ) in the reaction catalyzed by pyridine; dioxirane ( 9 ) or carbonyl oxide ( 10 ) is proposed as an intermediate.

Photochemical transfer of oxygen from selenoxide to sulfide

Die Selenoxide (I) reagieren mit Sulfiden (II) zu den Seleniden (III) und den Sulfoxiden (IV).

Formation and reaction of N-substituted peroxycarboximidic acids from α-azobenzyl hydroperoxides by pyridine-catalyzed reaction

Abstract α-Azobenzyl hydroperoxides ( 4 ) isomerize to N-(4-bromoanilino)-peroxycarboximidic acids ( 5 ), which are transformed into benzoic acids ( 6 ), by the pyridine-catalyzed reaction.

A new epoxidation reaction: base-catalysed stereospecific epoxidation with α-azohydroperoxides

A new Stereospecific epoxidation with α-azohydroperoxides (1) in basic media is reported. cis- and trans-Stilbene gave the corresponding epoxides stereospecifically in the reaction with α-azohydroperoxides (1a–d) catalysed by pyridine or sodium hydroxide. Similarly, cis-β-methylstyrene gave the corresponding cis-epoxide. Cyclohexene, trinorborn-2-ene, and tetramethylethylene all gave epoxides in good to high yield in the reaction with (1a–d) under the basic conditions. The mechanism of this novel base-catalysed epoxidation is discussed.

A novel base-catalysed oxidation of sulphides with an α-azohydroperoxide

The α-azohydroperoxide (1) in the presence of pyridine oxidises aryl sulphides cleanly to sulphoxides; the dioxirane (2) is proposed as the intermediate.