Synthesis and in vitro evaluation of 2,3-dimethoxy-5-(fluoroalkyl)-substituted benzamides: high-affinity ligands for CNS dopamine D2 receptors

J Med Chem. 1991 May;34(5):1612-24. doi: 10.1021/jm00109a013.


A number of 2,3-dimethoxy-5-(fluoroalkyl)-N-[(1-ethyl-2- pyrrolidinyl)methyl]benzamides (with or without a 6-hydroxy group) were synthesized and evaluated as dopamine D2 receptor ligands. The parent acids were synthesized via the Claisen rearrangement of the appropriate O-allyl ethers, which were derived from o-vanillic acid or 2,3-dimethoxysalicylic acid. A decrease in reactivity was found to be characteristic of pentasubstituted benzoates, and difficulties were encountered with the introduction of fluorine onto the ethyl side chains. The (fluoroethyl)- and (fluoropropyl)salicylamides were 5 times more potent than the corresponding benzamides in inhibiting [3H]spiperone binding to the D2 receptor. These (fluoroalkyl)salicylamides are of potential value for in vivo positron emission tomography (PET) studies upon the basis of their relatively selective, high potency binding affinity for the D2 receptor.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Benzamides / chemical synthesis*
  • Benzamides / metabolism
  • Benzamides / pharmacology
  • Binding, Competitive
  • Brain / drug effects
  • Brain / metabolism
  • Central Nervous System / drug effects*
  • Central Nervous System / metabolism
  • Chemical Phenomena
  • Chemistry
  • Ligands
  • Rats
  • Rats, Inbred Strains
  • Receptors, Dopamine / drug effects*
  • Receptors, Dopamine D2
  • Structure-Activity Relationship


  • Benzamides
  • Ligands
  • Receptors, Dopamine
  • Receptors, Dopamine D2