Mg0-promoted selective C–F bond cleavage of trifluoromethyl ketones: a convenient method for the synthesis of 2,2-difluoro enol silanes

(Note: The full text of this document is currently only available in the PDF Version )

Hideki Amii, Takeshi Kobayashi, Yasushi Hatamoto and Kenji Uneyama


Abstract

2,2-Difluoro enol silyl ethers were readily prepared by Mg0 promoted selective defluorination of trifluoromethyl ketones in the presence of TMSCl, which involves C–F bond cleavage.


References

  1. J. P. Whitten, C. L. Barney, E. W. Huber, P. Bey and J. R. McCarthy, Tetrahedron Lett., 1989, 30, 3649 CrossRef CAS; Z.-M. Qiu and D. J. Burton, J. Org. Chem., 1995, 60, 5570 CrossRef CAS; K. Iseki, Y. Kuroki, D. Asada and Y. Kobayashi, Tetrahedron Lett., 1997, 38, 1447 CrossRef CAS.
  2. M. Kuroboshi and T. Ishihara, Bull. Chem. Soc. Jpn., 1990, 63, 426.
  3. Base-catalysed dehydrofluorination of 2,2,2,-trifluoroethyl groups: J. A. Haward, W. H. Owton, J. M. Percy and M. K. Rock, Tetrahedon, 1995, 51, 10 289 Search PubMed; J. Ichikawa, T. Sonoda and H. Kobayashi, Tetrahedon Lett., 1989, 30, 1641 Search PubMed.
  4. Defluorination via Brook rearrangement for acylsilanes: F. Jin, Y. Xu and W. Huang, J.Chem. Soc., Perkin Trans. 1, 1993, 795 Search PubMed; T. Brigaud, P. Doussot and C. Portella, J. Chem. Soc., Chem. Commun., 1994, 2117 RSC.
  5. Reductive dechlorofluorination of α-chloro-α-alkoxy-βββ-trifluoropropionates: G.-Q. Shi and W.-L. Cai, J. Org. Chem., 1995, 60, 6289 Search PubMed.
  6. SN2' type reaction to trifluoromethyl groups: J.-P. Bégué, D. Bonnet-Delpon and M. H. Rock, Synlett, 1995, 659 Search PubMed.
  7. Reactions of the silyllithium and silylmagnesium reagents with trifluoromethyl ketones: I. Fleming, R. S. Roberts and S. C. Smith, J. Chem. Soc., Perkin Trans. 1, 1998, 1215 Search PubMed.
  8. K. Uneyama, K. Maeda, T. Kato and T. Katagiri, Tetrahedron Lett., 1998, 39, 3741 CrossRef CAS.
  9. K. Uneyama and T. Kato, Tetrahedron Lett., 1998, 39, 587 CrossRef CAS.
  10. For a recent review on metal-mediated C–F bond activation, see: J. Burdeniuc, B. Jedlicka and R. H. Crabtree, Chem. Ber./Recl., 1997, 130, 145 Search PubMed.
  11. A flask containing Mg turnings was flame-dried under under vacuum, cooled, and then flushed with argon. Commercially available Mg turnings (Nacalai tesque, Inc.) were used without further activation of the magnesium surface, such as iodine, dibromoethane or ultrasound treatment.
  12. Y. Ishino, Y. Kita, H. Maekawa, T. Ohno, Y. Yamasaki, T. Miyata and I. Nishiguchi, Tetrahedron Lett., 1999, 40, 1349 CrossRef CAS.
  13. Electroreductive defluorination of fluoromethylarenes: C. Saboureau, M. Troupel, S. Sibille and J. Périchon, J. Chem. Soc., Chem. Commun., 1989, 1138 Search PubMed; C. P. Andrieux, C. Combellas, F. Kanoufi, J.-M. Savéant and A. Thiébault, J. Am. Chem. Soc., 1997, 119, 9527 RSC.
  14. For are cent review, see: V. V. Grushin and H. Alper, Chem. Rev., 1994, 94, 1047 Search PubMed.
Click here to see how this site uses Cookies. View our privacy policy here.