Mechanistic studies of amination of ketenimines: Change of rate-determining step by N-substituents through electronic effects

Kuangsen Sung, Fu Lin Chen, Pin Mei Huang, Shu Min Chiang

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Vinylidenediamine intermediate was not found in amination reactions of N-i-propyl-p-substituted-phenylketenimines 3a-3e with n-BuNH2, but it was found in amination reactions of N-p-substituted-phenylphenylketenimines 1a-1c with n-BuNH2 by low-temperature 1H NMR spectrometer, indicating that the rate-determining step is changed from the first step (C=N addition) to the second step (tautomerization) when N-substituent of the ketenimines is changed from i-propyl group to p-substituted-phenyl group. Amination reactions of ketenimines 5 and 10 in a solvent with ε=35.9 were designed to explore electronic effects of N-substituents on the amination reactions by means of ab initio calculations. Computation results at level of MP2/6-31+G*//HF/6-31+G* (Onsager model) show that significant electronic stabilization of the first transition state involving C=N addition by N-phenyl group is the major factor causing the change of the rate-determining step for the amination reactions.

Original languageEnglish
Pages (from-to)171-181
Number of pages11
JournalTetrahedron
Volume62
Issue number1
DOIs
Publication statusPublished - 2006 Jan 2

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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