NMR and Theoretical Studies on the Conformational Preferences of Some Non-metal Coordinated N-Enoyl Systems Attached to Common Chiral Auxilaries

Authors

  • Rosmarbel Morales-Nava Universidad Autónoma del Estado de Morelos
  • Alejandro Ramírez-Solís INSA-Université de Toulouse + On sabbatical leave from Facultad de Ciencias. Universidad Autónoma del Estado de Morelos
  • Mario Fernández-Zertuche Universidad Autónoma del Estado de Morelos

DOI:

https://doi.org/10.29356/jmcs.v58i2.162

Keywords:

Enoyl systems, conformational preferences, chiral auxiliaries, NMR shifts

Abstract

We report a systematic study of a series of N-enoyl systems attached to common oxazolidin-2-ones, oxazolidine-2-thiones and thiazolidine-2-thiones chiral auxiliaries in order to determine the most stable conformation of these compounds. 1H NMR studies show an anti-s-cis structure as the most stable conformation for these series of compounds. Density Functional Theory geometry optimizations and vibrational analysis using the b3lyp exchange-correlation functional with the standard 6-31g** basis sets were done, including solvent effects (chloroform and toluene). Gibbs free energy differences show that the anti-s-cis structures are the most stable conformers lying, on average, ca. 6 kcal/mol lower in energy than the syn-s-cis conformers, widely used to explain the structure and reactivity of N-enoyl systems.

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Author Biographies

Rosmarbel Morales-Nava, Universidad Autónoma del Estado de Morelos

Centro de Investigaciones Químicas

Alejandro Ramírez-Solís, INSA-Université de Toulouse + On sabbatical leave from Facultad de Ciencias. Universidad Autónoma del Estado de Morelos

Laboratoire de Physico-chimie de Nano-objets

Mario Fernández-Zertuche, Universidad Autónoma del Estado de Morelos

Centro de Investigaciones Químicas

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Published

2017-10-12

Issue

Section

Regular Articles