Synthesis and analysis of the all-(S) side chain of phosphomycoketides: a test of NMR predictions for saturated oligoisoprenoid stereoisomers

J Org Chem. 2013 May 17;78(10):4913-8. doi: 10.1021/jo4005298. Epub 2013 Apr 25.

Abstract

(4S,8S,12S,16S,20S)-Pentamethylheptacosan-1-ol has been synthesized and analyzed by resolution-enhanced NMR spectroscopy with the aid of a recent set predicted spectra of all its stereoisomers. The configuration was confirmed, but isomer purity of the sample (~70%) was lower than expected. A truncated analogue, (2S,6S,10S,14S)-2,6,10,14-tetramethylhenicosan-1-ol TBDPS ether, was prepared from a late stage synthetic intermediate. Analysis of its spectra confirmed the configuration and showed that the sample was isomerically pure. The results suggest that a late-stage epimerization, not a failure of an asymmetric synthesis step, caused the formation of minor stereoisomers in the sample of pentamethylheptacosan-1-ol. The study shows the value of the predicted set of oligoisoprenoid spectra and further extends the predictive model to a new subclass of compounds.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fatty Alcohols / analysis*
  • Fatty Alcohols / chemical synthesis*
  • Fatty Alcohols / chemistry
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Stereoisomerism
  • Terpenes / chemistry*

Substances

  • Fatty Alcohols
  • Terpenes