Photochemical reactions of aromatic compounds. XLVI. Stereochemical reaction courses in the photolytic ring-cleavage reactions of diarylcyclobutanes: Implications of conformation-controlled orbital interactions in the excited-state chemistry.
スポンサーリンク
概要
- 論文の詳細を見る
The photolyses of <I>cis</I>-<I>transoid</I>-<I>cis</I>-cyclobutadiindene (<B>1</B>), <I>cis</I>-2-phenylcyclobut[<I>a</I>]indene (<B>2</B>), <I>cis</I>-1,2-diphenylcyclobutane (<B>3</B>), the trans isomer (<B>4</B>), and its dimethyl (<B>5</B>) and tetramethyl (<B>6</B>) derivatives have been investigated to explore stereoelectronic factors controlling the excited-state reaction courses for the ring cleavages. The symmetric ring cleavage occurs regiospecifically in the cases of <B>1–3</B> and with 98% specificity in the case of <B>4</B>. The photolysis of <B>5</B> results in both the symmetric and the asymmetric cleavages in a ca. 1 : 3 ratio accompanied by substantial losses of stereointegrity in the olefin formation, and the regiospecific asymmetric cleavage occurs in the case of sterically more congested <B>6</B>. The ring-cleavage efficiencies systematically decrease in the order <B>1</B>><B>2</B>><B>3</B>><B>4</B>><B>5</B>><B>6</B> and reveal negative temperature dependences, particularly in the cases of <B>1</B>, <B>5</B>, and <B>6</B>. The features of the reactions are in parallel with stable conformations and conformational mobilities of the aryl groups associated with different π–σ orbital interactions, while the spectroscopic properties of the cyclobutanes are essentially identical with those of benzene chromophores with little electronic perturbation. The photolytic ring-cleavage reactions are discussed in terms of crossing from the localized <SUP>1</SUP>π,π<SUP>*</SUP> state to a σ<SUP>*</SUP> hypersurface, in which conformation-controlled orbital interactions play important roles. The final products are formed via a pericyclic minimum which might be biradicaloid in nature.
- 公益社団法人 日本化学会の論文
著者
-
Yanagida Shozo
Department of Applied Chemistry, Faculty of Engineering, Osaka University
-
Pac Chyongjin
Department of Chemical Process Engineering, Faculty of Engineering, Osaka University
-
Go-an Kazuyoshi
Department of Chemical Process Engineering, Faculty of Engineering, Osaka University
関連論文
- Electron Transfer in Tris(bipyridine)ruthenium(II) Complex Films on ITO
- Production of Alkane and Alkene from CO_2 by a Petroleum-Degrading Bacterium
- Participation of a Chain Mechanism in Efficient Monomerization of Dimethylthymine Cyclobutane Dimer Photosensitized by a Flavin in the Presence of Perchloric Acid
- Emissive Triplex Formation in a Methylene-Bridged A-D-D' System. Intramolecular Long-Range Electron Transfer^1
- Redox-photosensitized reactions. XV. Photosensitized and direct photolytic isomerizations of the tetrahydro dimers of 1-benzylnicotinamide.
- Synthesis and alkali-cation complexing properties of 12-crown-4 derivatives.
- Photochemical reactions of aromatic compounds. XXXVII. Solvent effects on fluorescence quenching and photoreactions of naphthonitrile-olefin and furan systems. Qualitative consideration on electronic structures and reactivities of nonemissive exciplexes.
- Studies on Nitrile Salts. IV. Trimerization of Nitriles to 1,3,5-Triazines by the Combined Catalyst PCl5–HCl
- Redox-photosensitized reactions. XIV. Photochemistry of 4-alkylated NADH models, 1-benzyl-4-(1-hydroxyalkyl)-1,4-dihydronicotinamides.
- Molecular structures of diarylcyclobutanes associated with reactivities in ring-cleavage reactions: Implications of conformationally controlled through-bond coupling.
- The X-ray structure determination of heptaethylene glycol-Sr(SCN)2.
- Photochemical reactions of aromatic compounds. XLII. Photosensitized reactions of some selected diarylcyclobutanes by aromatic nitriles and chloranil. Implications of charge-transfer contributions on exciplex reactivities.
- Studies on Nitrile Salts. I. Dimerization of Nitriles Having α-Hydrogen in the Presence of Hydrogen Chloride
- Thermal ring-splitting reactions of diarylcyclobutanes: Significance of steric effects on orbital interactions in transition states and biradical intermediates.
- The Reaction of Nitriles with Phosgene. VII. Synthesis of α,β-Unsaturated Isocyanates
- Studies on Nitrile Salts. II. A Facile One-step Synthesis of the Pyrimidine Nucleus
- Photochemical reactions of aromatic compounds. XLVI. Stereochemical reaction courses in the photolytic ring-cleavage reactions of diarylcyclobutanes: Implications of conformation-controlled orbital interactions in the excited-state chemistry.
- The Reaction of Nitriles with Phosgene. V. Cyclization Reactions of N-(α-Chlorobenzylidene)carbamoyl Chloride
- Reactions of perfluoro-2-methyl-2-pentene with carboxylic acids, alcohols, and some cyclic amides. A new fluorinating reagent.
- The synthesis and cation-complexing ability of alkyl crown ethers.
- Metal-ion complexation of noncyclic poly(oxyethylene) derivatives. II. PMR studies of the complexation with alkali and alkaline-earth metal cations.
- Studies on Nitrile Salts. III. Dimerization of Nitriles Having No α-Hydrogen with Hydrogen Chloride