Ab initio studies of three-membered ring formation through intramolecular nucleophilic substitution
✍ Scribed by Han, In-Suk; Kim, Chang Kon; Kim, Chan Kyung; Lee, Bon-Su; Lee, Ikchoon
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 332 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
Three-membered ring 3MR forming processes of y y Ž . Ž X-CH -CH -F and CH -C -Y -CH -F X CH , O, or S and 2 2 2 2 2
. Ž . Y 0 or S through a gas phase neighboring group mechanism S i are N studied theoretically using the ab initio molecular orbital method with the 6᎐31 q G* basis set. When electron correlation effects are considered, the Ž / . Ž 0 .
y 1 activation ⌬G and reaction energies ⌬G are lowered by ca. 10 kcal mol , indicating the importance of the electron correlation effect in these reactions. The Ž / .
/ contribution of entropy of activation yT⌬ S at 298 K to ⌬G is very small, and the reactions are enthalpy controlled. The ⌬G / and ⌬G 0 values for these ring closure processes largely depend on the stabilities of the reactants and the heteroatom acting as a nucleophilic center. The Bell᎐Evans᎐Polanyi principle applies well to all these reaction series.