• Title/Summary/Keyword: cycloaddition

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Explorations of the Heteroatom Directed Photoarylation Reaction. A Review of the Photoinitiated Intramolecular Cycloaddition Reactions of Ylide Systems

  • Dittami, James P.
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.21-35
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    • 2003
  • The photoinitiated intramolecular ylide-olefin addition has been developed as an approach for the construction of one ring and two chiral centers, two rings and three chiral centers or three rings and six chiral centers in a single experimental operation from relatively simple starting materials. These investigations have uncovered several interesting and unusual reactions, which are sensitive to controls such as wavelength, temperature and solvent.

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Ab Initio Study on the Psoralen(I)

  • Kim, Ja-Hong;Kwon, O-Hyung
    • Journal of Photoscience
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    • v.12 no.3
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    • pp.185-186
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    • 2005
  • The electronic structure of photoskinsensitizing psoralens has been investigated by the ab initio calculations. The photocycloaddition reaction of 8-methoxypsoralen with thymine is studied as a model for the photosensitizing reaction of psoralen with DNA bases. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of Syn, H-H, Syn, H-T formed through [2+2] addition reaction between the 3,4-double bonds of 8-methoxypsoralen and 5,6-double bond of thymine base.

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Regioselectivity in the Cycloaddition Reactions of t-Butyl Trimethylsilyl Thioketone with 1,3-Butadienes

  • Kang, Kyung-Tae;Park, Chi-Hyo;Yoon, Ung-Chan
    • Bulletin of the Korean Chemical Society
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    • v.13 no.1
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    • pp.41-45
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    • 1992
  • Thermal cycloaddition of t-butyl trimethylsilyl thioketone (1) with 2-substituted dienes such as isoprene and 2-trimethylsilyloxy-1,3-butadiene occurred smoothly at 80${\circ}C$ to afford regioiomeric mixtures of cycloadducts. On the other hand, similar treatment of 1 with 1-substituted dienes such as trans-1,3-pentadiene, 1-methoxy-and 1-acetoxy-1,3-butadiene and Danishefsky's diene afforded a single regioisomeric adduct, respectively. Protodesilylation of the silylated adducts 8 and 11 could also be performed with ease.

Synthetic Studies on Carbapenam Skeletons (Ⅱ)

  • 서민효;구양모;이윤영
    • Bulletin of the Korean Chemical Society
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    • v.19 no.3
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    • pp.335-339
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    • 1998
  • Syntheses of carbapenam skeletons were achieved from 3-benzyloxypropanal through 1,3-dipolar cycloaddition. 3-Benzyloxypropanal was reacted with N-hydroxyglycine ester to give C-(2-benzyloxyethyl)-N-alkoxycarbonylmethylnitrone (6). 1,3-Dipolar cycloaddition of the nitrone with ethyl crotonate gave 3-(2-benzyloxyethyl)isoxazolidine (7). Compound 7 was transformed to 4-(2-hydroxyethyl)-2-azetidinone (11). Compound 11 was converted to 4-(2-iodoethyl)-2-azetidinone (13) or 4-phenylthiocarbonylmethyl-2-azetidinone (16) which was cyclized to give 6-(1-hydroxyethyl)carbapenam-3-carboxylate (14, 17).

Total synthesis of Antofine by using Intramolecular 1.3-dipolar cycloaddition of Azidealkene

  • Lee, Jae-Kwang;Lee, Tae-Ho;Song , So-Young
    • Proceedings of the PSK Conference
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    • 2002.10a
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    • pp.362.2-362.2
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    • 2002
  • Antofine belongs to the Phenathroindolizidine group of alkaloids. This natural products exhibit interesting biological properties such as antitumour activity. and anti-inflammentory. Wittig reaction of phenathrenealdehyde with the phosponium salt provided the phenathreneazidealkene in good yield. Intramolecular 1.3-dipolar cycloaddition of the resulting azidealkent in refluxing benzene proceeded the imine. It was reduced with cyanoborohydride of Noyori's Asymmetric Hydrogenation. (omitted)

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Immobilization of Homogeneous Catalyst on Functionalized Carbon Nanotube via 1,3-Dipolar Cycloaddition Reaction and its Ethylene Polymerization (1,3-Dipolar cycloaddition 반응을 통해 기능화된 carbon nanotube 표면 위에 균일계 촉매 담지 및 에틸렌 중합)

  • Lee, Jeong Suk;Lee, Se Young;Lee, Jin Woo;Ko, Young Soo
    • Korean Chemical Engineering Research
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    • v.54 no.4
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    • pp.574-581
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    • 2016
  • In this study, CNT functionalized with pyrrolidine ring via 1,3-dipolar cycloaddition reaction with various amino acid and aldehyde was synthesized. Metallocene was subsequently immobilized on the functionalized CNT and CNT/polyethylene composite was prepared via in-situ ethylene polymerization. The polymerization activities of metallocene supported on CNT functionalized with glycine and benzaldehyde (Gly+BA-CNT) were similar to those of metallocene supported on CNT functionalized with N-benzyloxycarbonylglycine and paraformaldehyde (Z-Gly+PFA-CNT) although its Zr content was lower than that of Z-Gly+PFA-CNT. In the case of metallocene supported on Z-Gly+PFA-CNT, the even distribution of active sites hindered the diffusion of ethylene monomer and cocatalyst MAO due to steric hindrance during ethylene polymerization. Compared to polyethylene produced from homogeneous metallocene catalysts, CNT/PE composites had a higher initial degradation temperature ($T_{onset}$) and maximum mass loss temperature ($T_{max}$). It suggests that pyrrolidine functionalized CNT is uniformly dispersed and strongly interacted with the PE matrix, enhancing the thermal stability of PE.