Synthesis and characterization of d5-barbarin for use in barbarin-related research

Sucheta Kudrimoti, Jacob Machin, Adedamola S. Arojojoye, Samuel G. Awuah, Rodney Eisenberg, Clara Fenger, George Maylin, Andreas F. Lehner, Thomas Tobin

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Based on structural similarities and equine administration experiments, Barbarin, 5-phenyl-2-oxazolidinethione from Brassicaceae plants, is a possible source of equine urinary identifications of aminorex, (R,S)-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine, an amphetamine-related US Drug Enforcement Administration (DEA) controlled substance considered illegal in sport horses. We now report the synthesis and certification of d5-barbarin to facilitate research on the relationship between plant barbarin and such aminorex identifications. D5-barbarin synthesis commenced with production of d5-2-oxo-2-phenylacetaldehyde oxime (d5-oxime) from d5-acetophenone via butylnitrite in an ethoxide/ethanol solution. This d5-oxime was then reduced with lithium aluminum hydride (LiAlH4) to produce the corresponding d5-2-amino-1-phenylethan-1-ol (d5-phenylethanolamine). Final ring closure of the d5-phenylethanolamine was performed by the addition of carbon disulfide (CS2) with pyridine. The reaction product was purified by recrystallization and presented as a stable white crystalline powder. Proton NMR spectroscopy revealed a triplet at 5.88 ppm for one proton, a double doublet at 3.71 ppm for one proton, and double doublet at 4.11 ppm for one proton, confirming d5-barbarin as the product. Further characterization by high resolution mass spectrometry supports the successful synthesis of d5-barbarin. Purity of the recrystallized product was ascertained by High Performance Liquid Chromatography (HPLC) to be greater than 98%. Together, we have developed the synthesis and full characterization of d5-barbarin for use as an internal standard in barbarin-related and equine forensic research.

Original languageEnglish
Pages (from-to)42-46
Number of pages5
JournalDrug Testing and Analysis
Issue number1
StatePublished - Jan 2023

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd.


  • Barbarea vulgaris
  • aminorex
  • d-barbarin
  • equine forensic science
  • internal standard

ASJC Scopus subject areas

  • Analytical Chemistry
  • Environmental Chemistry
  • Pharmaceutical Science
  • Spectroscopy


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