A study of influence of temperature and N , N -acyl protected keto ylides structure on their predominant transformations

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• 作者：D. A. Chuvashov ; I. V. Vakulin ; F. Z. Galin and R. F. Talipov
• 关键词：N ; N ; acyl protected keto ylides ; Intramolecular cyclization ; Effect of structure ; Thermal dependencies of Gibbs free energy of reactions ; DFT calculation
• 刊名：Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
• 出版年：2007
• 出版时间：August, 2007
• 年：2007
• 卷：118
• 期：2
• 页码：363-369
• 全文大小：155 KB

文摘

The effect of temperature and keto ylides structure on preference of their intramolecular cyclization leading to N-containing heterocyclic compounds or linear products formation has been investigated at the B3LYP/6-31G(d,p) level of theory. It has been determined that the thermodynamic advantage of the cyclization reactions of ylides increases with temperature, while Gibbs free energies of linear products formation reactions depend insignificantly on temperature. The Wittig and the Corey–Chaykovsky reactions are least probable in the case of the sulfonium and ammonium ylides considered. However, for phosphonium ylides the Wittig reaction must be considerably preferable in comparison with other routes, while behavior of the arsonium ylides is predicted to be more complex. Research of S-ylides transformations shows that formation of methylthio-substituted heterocycles with five-, six- or seven- membered rings is possible from a thermodynamic standpoint, while conversion of the corresponding ylide to a four-membered heterocycle is disadvantageous. Presence of a methyl substituent and its position in the ylide carbon chain depends ambiguously on the behavior of sulfur keto ylides.