NMR and Theoretical Studies on the Conformational Preferences of Some Non-metal Coordinated N-Enoyl Systems Attached to Common Chiral Auxilaries
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.
| Main Authors: | , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedad Química de México A.C.
2014
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1870-249X2014000200001 |
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