• Title/Summary/Keyword: Cycloaddition reactions

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Density Functional Study on [3+2]-Dipolar Cycloaddition Reaction of the N-heterocyclic Carbene Boryl Azide with Olefins

  • Zhang, Xing-Hui;Wang, Ke-Tai;Niu, Teng;Li, Shan-Shan
    • Bulletin of the Korean Chemical Society
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    • v.35 no.5
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    • pp.1403-1408
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    • 2014
  • The cycloaddition reactions of the N-heterocyclic carbene boryl azide with methyl acrylate, butenone, and hexafluoropropene have been investigated theoretically. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum model (PCM) for the solvent (C6H6). The title reaction could produce 4- and 5-substituted 1,2,3-triazolines, respectively. The reaction systems have the higher chemical reactivity with the low barriers and could be favored. Yet the smaller differences have been found to occur in energetics, and the cycloaddition reactions occur for s-trans conformations over s-cis conformations. The calculations indicated that the cycloaddition reaction of the alkenes have certain regioselectivity.

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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    • v.2 no.3
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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.

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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Theoretical Study of Cycloaddition Reactions of C60 on the Si(100)-2×1 Surface

  • Rashid, Mohammad Harun Or;Lim, Chul-Tack;Choi, Cheol-Ho
    • Bulletin of the Korean Chemical Society
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    • v.31 no.6
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    • pp.1681-1688
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    • 2010
  • Density functional theory was adopted to study the various surface products and their reaction channels focusing on the on-dimer configuration which has not been suggested before. Energetic results show that the most stable on-dimer configuration is the 6,6-[2+2] structure which resembles the typical [2+2] cycloaddition product. The 6,6-[2+2] product is also more stable than any other possible surface structures of inter-dimer configuration further suggesting its existence. Potential energy surface scan along various possible initial surface reactions show that some of the possible on-dimer surface products require virtually no reaction barrier indicating that initial population of on-dimer surface products is thermodynamically determined. Various surface isomerization reaction channels exist further facilitating thermal redistribution of the initial surface products.