Conformational Evaluation of Indol-3-yl-N-alkyl-glyoxalylamides and Indol-3-yl-N,N-dialkyl-glyoxalylamides

David Mansell, Simon D. Brandt, Sabiya Nasima, Nicola Turvey, John F. Alder, Sally Freeman, Carl H. Schwalbe

Research output: Contribution to journalArticle

Abstract

Restricted rotation in indol-3-yl-N-alkyl- and indol-3-yl-N,N-dialkyl-glyoxalylamides can in principle give the syn-periplanar and anti-periplanar rotamers. In asymmetrically disubstituted glyoxalylamides, steric effects lead to the occurrence of both rotamers, as observed by NMR spectroscopy. The predominant peak corresponds with the anti rotamer, in which the bulkier alkyl group is orientated trans to the amide carbonyl group. In monoalkylated glyoxalylamides, only one set of peaks is observed, consistent with the presence of only one rotamer. Crystal structures of 5-methoxyindole-3-yl-N-tert-butylglyoxalylamide, indole-3-yl-N-tert-butylglyoxalylamide, and indole-3-yl-N-isopropylglyoxalylamide reported here reveal a syn conformation held by an intramolecular N-HO hydrogen bond.
Original languageEnglish
Pages (from-to)156-166
Number of pages11
JournalSpectroscopy letters
Volume42
Issue number3
Early online date25 Mar 2009
DOIs
Publication statusPublished - Apr 2009

Keywords

  • amides
  • crystal structure
  • glyoxalylamides
  • indole
  • intramolecular hydrogen bond
  • nuclear magnetic resonance
  • rotamers

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