Difluoromethyl Bioisostere: Examining the "Lipophilic Hydrogen Bond Donor" Concept

J Med Chem. 2017 Jan 26;60(2):797-804. doi: 10.1021/acs.jmedchem.6b01691. Epub 2017 Jan 17.

Abstract

There is a growing interest in organic compounds containing the difluoromethyl group, as it is considered a lipophilic hydrogen bond donor that may act as a bioisostere of hydroxyl, thiol, or amine groups. A series of difluoromethyl anisoles and thioanisoles was prepared and their druglike properties, hydrogen bonding, and lipophilicity were studied. The hydrogen bond acidity parameters A (0.085-0.126) were determined using Abraham's solute 1H NMR analysis. It was found that the difluoromethyl group acts as a hydrogen bond donor on a scale similar to that of thiophenol, aniline, and amine groups but not as that of hydroxyl. Although difluoromethyl is considered a lipophilicity enhancing group, the range of the experimental Δlog P(water-octanol) values (log P(XCF2H) - log P(XCH3)) spanned from -0.1 to +0.4. For both parameters, a linear correlation was found between the measured values and Hammett σ constants. These results may aid in the rational design of drugs containing the difluoromethyl moiety.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anisoles / chemical synthesis
  • Anisoles / chemistry
  • Hydrocarbons, Fluorinated / chemical synthesis
  • Hydrocarbons, Fluorinated / chemistry*
  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions
  • Lewis Acids / chemical synthesis
  • Lewis Acids / chemistry
  • Proton Magnetic Resonance Spectroscopy
  • Sulfides / chemical synthesis
  • Sulfides / chemistry

Substances

  • Anisoles
  • Hydrocarbons, Fluorinated
  • Lewis Acids
  • Sulfides