- Synthesis and photochemical behaviour of 4-nitroimidazoles in the presence of oxygen
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Synthesis and photochemical properties of 1-aryl-4-nitroimidazoles are described. These compounds are good sensitizers of superoxide ion. Only 1-phenyl-2-methyl-4-nitroimidazole is a photosensitizer of singlet oxygen.
- D'Auria, Maurizio,D'Onofrio, Franco,Suwinski, Jerzy,Swierczek, Krzysztor
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p. 3899 - 3906
(2007/10/02)
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- THE PHOTOCHEMICAL PREPARATION OF OZONIDES BY ELECTRON-TRANSFER PHOTO-OXYGENATION OF EPOXIDES
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9,10-Dicyanoanthracene (DCA) sensitizes the electron-transfer photo-oxygenation of epoxides in oxygen-saturated acetonitrile to form ozonides.Epoxides with oxidation potentials lower than 2 V vs SCE quench the fluorescence of DCA and are converted to the
- Schaap, A. Paul,Siddiqui, Shahabuddin,Prasad, Girija,Palomino, Eduardo,Sandison, Mark
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p. 2229 - 2236
(2007/10/02)
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- Photoinduced Electron Transfer Reaction. Part 3. 9,10-Dicyanoanthracene-sensitized Photo-oxidation of Electron-rich Stilbene Oxides
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The 9,10-dicyanoanthracene (DCA)-sentisized photo-oxygenation of the electron-rich stilbene oxides (1) gives the ozonides (2) almost quantitatively.The fluorescence of DCA is quenched by (1) at a diffusion-controlled rate and the above reaction is quenched by polymethoxybenzenes which indicates that an electron transfer mechanism is involved.The quantum yield for ozonide formation varies from 0.6 for trans-2-(4-methoxyphenyl)-3-phenyloxirane (1d) to 2.4 for trans-2,3-bis(4-methoxyphenyl)-2,3-diethyloxirane (1h), suggesting a duplex reaction mechanism such as photo-oxygenation by superoxide and a Barton mechanism after the initial electron transfer from the epoxides (1) to the excited singlet state of DCA.
- Futamura, Shigeru,Kusunose, Shosaku,Ohta, Hiroyuki,Kamiya, Yoshio
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- PHOTO- AND THERMOINDUCED GENERATION OF 1,3-DIARYL CARBONYL YLIDES FROM 2,3-DIARYLOXIRANES. 1,3-DIPOLAR CYCLOADDITIONS TO DIPOLAROPHILES
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A group of symmetrically substituted 2,3-diaryloxiranes have been studied as photoprecursprs for carbonyl ylides.The stereochemistry of the adducts obtained upon interception of these 4n pi-transient systems with a variety of dipolarophiles provides information on the mode(s) of electrocyclic opening of the oxiranes to carbonyl ylides, as well as the mechanism of the 4n+2 cycloaddition process.The stereochemistry of the dipolarophiles is preserved in the cycloadducts, which is consistent with a concerted addition process; however, solvent effects, steric hindrance, and possibly secondary orbital overlap factors all may play a role in determining the product distribution.
- Wong, J. P. K.,Fahmi, A. A.,Griffin, G. W.,Bhacca, N. S
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p. 3345 - 3356
(2007/10/02)
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