Reinvestigation of the Absolute Configurations of Chiral β-Mercaptoalkanones Using Vibrational Circular Dichroism and 1H NMR Analysis

Christiane Kiske, Svenja Nörenberg, Miriam Ecker, Xingyue Ma, Tohru Taniguchi, Kenji Monde, Wolfgang Eisenreich, Karl Heinz Engel

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The absolute configurations of chiral β-mercaptoalkanones were previously assigned on the basis of the 1H NMR anisotropy method using (S)-2-methoxy-2-(1-naphthyl)propionic acid ((S)-MαNP) as the chiral auxiliary. This study presents a reinvestigation of the configurations of 4-mercapto-2-pentanone 1, 4-mercapto-2-heptanone 2, and 2-mercapto-4-heptanone 3. Enantiomers of 1, 2, and 3 were obtained by lipase-catalyzed hydrolyses of the respective acetylthioalkanones. Upon derivatization with (S)-MαNP, the configurations of the reaction products were deduced based on the order of the HPLC elution of the diastereoisomeric thioesters, assuming that the sector rule previously developed for secondary alcohols is also valid for thiols. In addition, the configurations were experimentally determined by vibrational circular dichroism (VCD) and 1H NMR analyses after esterification with (R)-hydratropic acid (HTA) and 2-methoxy-2-phenylacetic acid (MPA). The assignments of the configurations using VCD and NMR analyses of HTA- and MPA-thioesters were in agreement. However, they were opposite to those deduced for (S)-MαNP thioesters via the sector rule. Consequently, the formerly assigned configurations of β-mercaptoalkanones deduced via investigation of (S)-MαNP-derivatives have to be revised.

Original languageEnglish
Pages (from-to)8563-8571
Number of pages9
JournalJournal of agricultural and food chemistry
Volume64
Issue number45
DOIs
StatePublished - 16 Nov 2016

Keywords

  • 2-mercapto-4-alkanones
  • 4-mercapto-2-alkanones
  • H NMR spectroscopy
  • VCD
  • absolute configuration
  • lipase

Fingerprint

Dive into the research topics of 'Reinvestigation of the Absolute Configurations of Chiral β-Mercaptoalkanones Using Vibrational Circular Dichroism and 1H NMR Analysis'. Together they form a unique fingerprint.

Cite this