• 제목/요약/키워드: Photoaddition

검색결과 27건 처리시간 0.022초

Photoaddition Reactions of N-Methylthiophthalimide with $\alpha$-Silyl-n-electron Donors via Single Electron Transfer-Desilylation and Hydrogen Atom Abstraction Pathways

  • Yoon, Ung-Chan;Oh, Sun-Wha;Moon, Seong-Chul;Hyung, Tae-Gyung
    • Journal of Photoscience
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    • 제9권1호
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    • pp.17-22
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    • 2002
  • Studies have been conducted to explore photoaddition reactions of N-methylthiophthalimide with $\alpha$-silyl-n-electron donors Et$_2$NCH$_2$SiMe$_3$, n-PrSCH$_2$SiMe$_3$ and EtOCH$_2$SiMe$_3$. Photoaddition of $\alpha$-silyl amine Et$_2$NCH$_2$SiMe$_3$ to N-methylthiophthalimide occurs in $CH_3$CN and benzene to produce non-silicon containing adduct in which thiophthalimide thione carbon is bonded to $\alpha$-carbon of $\alpha$-silyl amine in place of the trimethylsilyl group. In contrast, photoaddition of EtOCH$_2$SiMe$_3$ to N-methylthiophthalimide generates two diastereomeric adducts in which thiophthalimide thione carbon is connected to $\alpha$-carbon of $\alpha$-silyl ether in place of u-hydrogen. Based on a consideration of the oxidation potentials of u-silyl-n-electron donors and the nature of photoadducts, mechanism for these photoadditions involving single electron transfer(SET) -desilylation and H atom abstraction pathways are proposed.

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테트라메틸에틸렌에 대한 트란스-1,2-비스피라질에틸렌의 광첨가반응 (Photoaddition Reactions of trans-1,2-Bispyrazylethylene to Tetramethylethylene)

  • 심상철;조진호
    • 대한화학회지
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    • 제23권5호
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    • pp.325-328
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    • 1979
  • 트란스-1,2-비스피라질에틸렌(BPE)과 테트라메틸에틸렌(TME)용액에 빛을 쪼이면 이에대응한 탄화수소와는 달리 자유라디칼중간체를 거쳐 광첨가반응이 일어난다. 이 광첨가반응은 BPE의 $^1(n,\;{\pi}^*)$ 상태가 어느정도 자유라디칼 성격을 띄어 TME로 부터 알릴위치에 있는 수소원자를 탈취하여 일어난다. 주생성물을 대롱 크로마토그래피와 진공분별승화법으로 분리하여 2,3-디메틸-5,6-비스피라질-2-헥센임을 밝혔다.

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Comparison of Photoaddition Reactions of Aromatic Carbonyl Compounds with Silyl Thioketene Acetal vs. Silyl Ketene Acetal

  • Lee, In Ok;Yoon, Ung Chan;Cho, Dae Won
    • Rapid Communication in Photoscience
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    • 제2권3호
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    • pp.76-78
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    • 2013
  • Photoaddition reactions of aromatic carbonyl compounds with silyl thioketene acetals have been explored. The results of this study show that the acetonphenone react with dimethyl substituted silyl thioketene acetal competitively via either single electron transfer (SET)-desilylation or [2+2]-cycloaddition pathways to produce b-hydroxyester and oxetanes. In contrast, photochemical reactions of the benzaldehyde with dimethyl substituted silyl thioketene acetal mainly lead to the formation of oxetanes arising by [2+2] cycloaddition. A comparison of the results with those of silyl ketene acetal revealed that replacement of sulfur atom in ${\alpha}$-silyl donor substrate bring about dramatic changes in chemoselectivities as well as excited state reaction mechanism.

PHOTOADDITION REACTIONS OF 1,4-DIPHENYLBUT-1-EN-3-YNE TO p-QUINONES

  • Kim, Sung-Sik;So, Mi-Hyun
    • Journal of Photoscience
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    • 제3권2호
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    • pp.61-64
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    • 1996
  • Photoaddition reactions of p-quinones to 1, 4-diphenylbubl-en-3-yne (BEY) have been investigated. Irradiation (300 nm) of BEY and 1, 4-benzoquinones in dichloromethane afforded quinone methides. I rradiation of 1, 4-naphthoquinone and BEY leaded to the formation of unstable spiro oxetene intermediate, followed by the rearrangement to give quinone methide, and finally the oxidative photocyclization. In contrast, irradiation 2, 3-dichloro-1, 4-naphthoquinone (or anthraquinone) and BEY yielded another type of quinone methides in one pot.

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Photochemistry of Conjugated Polyacethylenes: Photoaddition Reactions of 1-Phenyl-1,3,5-hexatriynes to Tetrahydrofuran

  • Shim, Sang Chul;Lee, Cheon Seok;Lee, Seong Taek
    • Bulletin of the Korean Chemical Society
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    • 제13권6호
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    • pp.654-658
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    • 1992
  • Photolysis of 1-phenyl-1,3,5-hexatriynes in deaerated tetrahydrofuran gave photoreduction and photoaddition products, while photolysis of 1-phenyl-1,3,5-hexatriynes in deaerated alcoholic solvents (methanol, i-propanol) yielded dark red products, probably oligomers or decomposition products of reactants, as exclusive major products. A plausible mechanism for the reaction is proposed.