- SPIN INVERSION IN THE 1,4-DIRADICAL DERIVED FROM 2,4,6-TRIISOPROPYLBENZOPHENONE: IMPORTANCE OF LONE-PAIR ORBITAL ROTATION.
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,6-Diisopropyl-2,2-dimethyl-1-phenyl-1,2-dihydrobenzocyclobuten-1-ol (2) was submitted to direct (254 nm) and sensitized photolysis and thermolysis in the absence or presence of oxygen. Direct photolysis (313 nm) of 2,4,6-triisopropylbenzophenone (1) was also performed in the absence or presence of oxygen. Interconversion between 1 and 2 and production of 1,3-diisopropyl-10,10-dimethylanthrone (3) and ,4-dihydro-1-hydroxy-6,8-diisopropyl-4,4-dimethyl-1-phenyl-2,3-benzo dioxin (4) happened in various quantum yields depending upon the reaction conditons. It is concluded that DR, which is generated from the direct photolysis of 1, is spin protected and its lifetime is determined by the rate of intersystem crossing.
- Ito,Matsuura
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- Electrocycloreversion of benzocyclobutenols promoted by photoinduced electron transfer
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Benzocyclobutenols 1 undergo electron-transfer induced electrocycloreversion to generate o-quinodimethane intermediates E-4 and Z-4, which then tautomerize to benzophenones 2. Evidence for the intermediates is provided by the trapping experiments and the laser flash photolysis experiments.
- Takahashi, Yasutake,Miyamoto, Kazuya,Sakai, Kazuhiro,Ikeda, Hiroshi,Miyashi, Tsutomu,Ito, Yoshikatsu,Tabohashi, Ken
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p. 5547 - 5550
(2007/10/03)
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- Novel Photoreversible Cyclization of Acyl-Substituted 2,4,6-Triisopropylbenzophenones
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A photoreversible cyclization of 3'(or 4')-X-2,4,6-triisopropylbenzophenones 1 (X=C6H5CO, 2,4,6-(i-Pr)3C6H2CO, CH3CO) into the corresponding 2 was investigated in benzene at 313 nm.When the meta (2,4,6-(i-Pr)3C6H2CO) derivative 1d was photolized, an addit
- Ito, Yoshikatsu,Giri, Brij Pal,Nakasuji, Masaaki,Hagiwara, Toshiya,Matsuura, Teruo
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p. 1117 - 1122
(2007/10/02)
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