Intramolecular nucleophilicS
N
2 substitution at the tetrahedral carbon atom: Anab initio study |
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Authors: | R M Minyaev V I Minkin |
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Institution: | (1) Institute of Physical and Organic Chemistry, Rostov State University, 194/2 prosp. Stachki, 344090 Rostov-on-Don, Russian Federation |
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Abstract: | Pentacoordination of carbon atom in bicyclic organic compounds of the pentalene type was studied by theab initio RHF/6-31G** and MP2(full)/6-31G** methods. It was shown that intramolecularS
N
2 reactions with energy barriers within the energy scale of NMR spectroscopy can occur in systems in which a linear orientation
of the attacking and leaving groups is realized. The barrier to the intramolecular nucleophilic substitution reaction in 2,3-dihydro-3-formylmethylenefuran
is 36.9 (RHF) and 27.7 kcal mol−1 (MP2) and decreases to 16.4 and 19.4 kcal mol−1, respectively, in the case of diprotonation at the O atoms in this system. For model pentalene type compounds containing
electron-deficient B atoms in the ring, theab initio calculations predict a further decrease in the barrier height (down to less than 10 kcal mol−1).
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1246–1256, July, 1999. |
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Keywords: | ab initio quantum-chemical calculations reaction pathway nucleophilic substitution pentacoordination of carbon atom |
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