Mechanism of 1,2-shift through π-complex transition state |
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引用本文: | 戴乾圜,周志刚,张大平.Mechanism of 1,2-shift through π-complex transition state[J].中国科学B辑(英文版),2000,43(6):576-586. |
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作者姓名: | 戴乾圜 周志刚 张大平 |
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摘 要: | A systematic calculation of the potential curves or surfaces for 1,2-shift has been realized by using MNDO or other models in MOPAC programs. By referring to the previous authors' viewpoints, the 1,2-shift can be divided into two categories. 1,2-electron-deficient shift is that the electronic configuration of the atom which accepts the migrating group is a cation or an electron-deficient atom, and 1,2-anion shift is the one that the accepted atom of the migration group is a negative ion. In terms of the experimental facts and the calculation of the potential surfaces, in electron-deficient shift such as Beckmann or Baeyer-Villiger rearrangement, the migration occurs through a transition complex formed between the 7i-bond and the cation or electron-deficient migrating group, but in anion shift such as Wittig or Stevens rearrangement, the electron pair in it-orbit excites at first to π* orbit, and then the migration occurs through the new formed complex between the anion migration group and the vacant rc
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关 键 词: | 1 2-shift rearrangement MNDO potential surface π-complex Wittig rearrangement. |
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