Synthesis and Rotational Isomerism of 1-Substituted Methyl (S)-[5-(2-Nitrophenyl)-1H-pyrazole-4-carbonyl]alaninates.
J Org Chem
; 81(1): 146-61, 2016 Jan 04.
Article
em En
| MEDLINE
| ID: mdl-26649855
ABSTRACT
Seven title compounds 12a-g and the (S)-prolinate analogue 13 were prepared in five steps from 2-nitrobenzoic acid (7). Reduction of the nitro group followed by derivatization of the so formed anilines 14 gave the N-alkyl-(15a-c), N-acyl-(16a,b and 19), and N-vinyl derivative 20. NMR spectra of (S)-alanine and (S)-proline derived compounds 12, 13, 14-16, 19, and 20 exhibited two sets of signals corresponding to pairs of conformational diastereomers. The free energy barriers of rotation, ΔG()298 = 82-86 kJ mol(-1), were determined by (1)H NMR for 12a, 12d, 12f, and 12g and evaluated by DFT calculations.
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01-internacional
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MEDLINE
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2016
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Article