Pentafluoroethylation Using Economical Ethyl Pentafluoropropionate

Ethyl pentafluoropropionate (1) is used as a source of pentafluoroethyl moiety. When 1 is added into a mixture of copper(I) chloride and potassium tert-butoxide, the pentafluoroethyl cuprate intermediate 2 is formed in situ.¹⁾ Upon addition of boronic acids or aryl bromides in air or under argon atmosphere, respectively, the cross coupling proceeds and the pentafluoroethyl moiety is introduced. One of the advantages of this reaction is that it is economical to insert the pentafluoroethyl moiety because of the use of inexpensive reagents. Furthermore, the three-component reaction using 1, acetyl aryls and hydrazines is reported and the pyrazole ring bearing pentafluoroethyl group is formed in high yields.²⁾

References

• 1) Direct Synthesis of Pentafluoroethyl Copper from Pentafluoropropionate as an Economical C₂F₅ Source: Application to Pentafluoroethylation of Arylboronic Acids and Aryl Bromides
  • H. Serizawa, K. Aikawa, K. Mikami, Org. Lett. 2014, 16, 3456.
• 2) Efficient one-pot synthesis of 5-perfluoroalkylpyrazoles by cyclization of hydrazone dianions
  • T. N. Ngo, S. A. Ejaz, T. Q. Hung, T. T. Dang, J. Iqbal, J. Lecka, J. Sévigny, P. Langer, Org. Biomol. Chem. 2015, 13, 8277.

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