Intramolecular hydrogen bonding between remote termini

Michael T. Huggins, David A. Lightner

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

[10]-Semirubin (1) and [20]-semirubin (2), with dipyrrinones covalently linked to C10 and C20 fatty acid chains, were synthesized following Friedel-Crafts acylation of the parent 9-H dipyrrinone, (4Z)-2,3,7,8-tetramethyl-(10H)-dipyrrin-1-one, with the diacid chlorides of decanedioic acid and eicosanedioic acid, respectively. Both of these bright yellow pigments are monomeric in CHCl3 solvent: MWobs=394±20 for 1 (formula weight 386), and 533±20 for 2 (formula weight 526) as determined by vapor pressure osmometry (VPO) measurements. In contrast, their methyl esters are dimeric in CHCl3. 1H{1H}-Nuclear Overhauser effects are found between the lactam NH and carboxylic acid OH of 1 and 2, consistent with the type of intramolecular hydrogen bonding found in bilirubin (the yellow pigment of jaundice) and its analogs.

Original languageEnglish
Pages (from-to)2279-2287
Number of pages9
JournalTetrahedron
Volume57
Issue number12
DOIs
StatePublished - Mar 17 2001
Externally publishedYes

Scopus Subject Areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

Keywords

  • Conformation
  • Hydrogen bonding
  • Pyrroles

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