Synthesis and antimalarial activities of fluoroalkyl derivatives of dihydroartemisinin

Fluoroalkyl ethers (4) of dihydroartemisinin (2) have been prepared by reaction of fluoroalkyl alcohols with dihydroartemisinin by different methods (BF3,Et2O or TMSCl catalysis or Mitsunobu reaction). Ethers 4a-d derived from primary fluoroalkyl alcohols were obtained in moderate to good yields by these methods. Ethers 4e-j have been prepared from fluoroalkyl secondary and tertiary alcohols and phenol using the Mitsunobu reaction. Although in vitro antimalarial activities of ethers toward Plasmodium falciparum W-2 asiatic strain are moderate, in vivo activities against Plasmodium berghei (NT 173) are excellent.