Chiral Recognition Studies of α-(Nonafluoro-tert-butoxy)carboxylic Acids by NMR Spectroscopy

J Org Chem. 2015 Jun 19;80(12):6267-74. doi: 10.1021/acs.joc.5b00706. Epub 2015 Jun 10.

Abstract

Three chiral α-(nonafluoro-tert-butoxy)carboxylic acids (R)-1, (RS)-2, (R)-3 were synthesized to examine their application as chiral solvating agents with amines. As a model compound, first (S)- and/or (RS)-α-phenylethylamine was used, and their diastereomeric salts were investigated by (1)H and (19)F NMR and ECD spectroscopy. The NMR spectroscopic studies were carried out at room temperature using the slightly polar CDCl3 and apolar C6D6 as solvents in 5 mM and 54 mM concentrations. The difference of the chemical shifts (Δδ) in the diastereomeric complexes is comparable with other, well-known chiral derivatizing and solvating agents (e.g., Mosher's acid, Pirkle's alcohol). Diastereomeric salts of racemic acids (RS)-1 and (RS)-2 with biologically active amines (1R,2S)-ephedrine and (S)-dapoxetine were also investigated by (19)F NMR spectroscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzylamines / chemistry
  • Carboxylic Acids / chemistry
  • Ephedrine / chemistry
  • Hydrocarbons, Fluorinated / chemical synthesis*
  • Hydrocarbons, Fluorinated / chemistry
  • Magnetic Resonance Spectroscopy / methods*
  • Naphthalenes / chemistry
  • Phenethylamines / chemistry*
  • Solvents / chemistry
  • Stereoisomerism

Substances

  • Benzylamines
  • Carboxylic Acids
  • Hydrocarbons, Fluorinated
  • Naphthalenes
  • Phenethylamines
  • Solvents
  • dapoxetine
  • Ephedrine
  • 1-phenethylamine