Efficient, practical and reproducible reactions of a commercial hydrochlorofluorocarbon

Abstract

We report a reliable and reproducible procedure for the conversion of readily-available hydrochlorofluorocarbon 1-chloro-2,2,2-trifluoroethane (HCFC-133a) to a metallated difluoroalkene (1-chloro-1-lithio-2,2-difluoroethene) which can be trapped with a range of electrophiles to afford high isolated yields of products. 1-Chloro-1-lithio-2,2-difluoroethene generated by our method reacts efficiently with aldehydes and ketones, Group (IV) halides, an epoxide and a sulfur electrophile. Less reactive, softer electrophiles fail to trap the reactive intermediate.

References

1. J. M. Percy, Contemp. Org. Synth., 1995, 4, 251.
2. F. G. Drakesmith, R. D. Richardson, O. J. Stewart and P. Tarrant, J. Org. Chem., 1968, 33, 286.
3. D. Masure, R. Sauvêtre, J. F. Normant and J. Villieras, Synthesis, 1976, 761.
4. K. Okuhara, J. Org. Chem., 1976, 41, 1487.
5. J. M. Percy, Top. Curr. Chem., 1997, 193, 131.
6. J. Burdon, P. L. Coe, I. B. Haslock and R. L. Powell, J. Fluorine Chem., 1997, 85, 151.
7. For a recent application of related allylic alcohols, see T. Takagi, N. Okikawa, S. Johnoshita, M. Koyama, A. Ando and I. Kumadaki, Synlett, 1996, 82 The groups of Hiyama and Kumadaki have described (independently) routes to these allylic alcohols, though the published characterisations are often far from complete. The former group worked from the increasingly less readily-available 2,2,2-trichloro-1,1,1-trifluoroethane (CFC-113a) while the latter obtained poor to moderate yields of products from expensive inhalation anaesthetic Halothane (HCFC-123B1)via the so-called abnormal Grignard reaction. See: T. Takagi, J. Takahashi, H. Nakatsuka, M. Koyama, A. Ando and I. Kumadaki, Chem. Pharm. Bull., 1996, 44, 280; T. Takagi, A. Takesue, A. Isowaki, M. Koyama, A. Ando and I. Kumadaki, Chem. Pharm. Bull., 1995, 43, 1071; T. Takagi, A. Takesue, M. Koyama, A. Ando, T. Miki, I. Kumadaki and T. Sato, J. Org. Chem., 1992, 57, 3921 Also: M. Fujita and T. Hiyama, Tetrahedron Lett., 1986, 27, 3655 See also: M. Fujita, T. Morita and T. Hiyama, Tetrahedron Lett., 1986, 27, 2135; M. Fujita and T. Hiyama, Bull. Chem. Soc. Jpn., 1987, 60, 4377; M. Fujita and T. Hiyama, Tetrahedron Lett., 1986, 27, 3659; M. Fujita, K. Kondo and T. Hiyama, Bull. Chem. Soc. Jpn., 1987, 60, 4385.
8. Tamura formed 5(62%) from benzaldehyde and 2,2-dichloro-1,1,1–trifluoroethane (HCFC-123): M. Tamura and A. Sekiya, J. Fluorine Chem., 1995, 71, 119.
9. For an electrochemical approach, see T. Shono, N. Kise and H. Oka, Tetrahedron Lett., 1991, 32, 6567.
10. In contrast, Drakesmith reported that these silane products were unstable and could not be isolated in reactions from HCFC-1122. See F. G. Drakesmith, O. J. Stewart and P. Tarrant, J. Org. Chem., 1968, 33, 472; The triethylsilane was prepared because the chlorotrimethylsilane adduct was simply too volatile to isolate in a pure state. The reader should note that the chlorotrimethylsilane adduct of the conjugate base of HFC-134a was never actually purified: I. Haslock, Ph.D. Thesis, University of Birmingham, 1995.
11. The trimethylstannane was reported in 40–45% yield from CFC-1112a: A. Runge and W. W. Sander, Tetrahedron Lett., 1990, 31, 5453.
12. M. J. Eis, B. Ganem and J. E. Wrobel, J. Am. Chem. Soc., 1984, 106, 3693 similar chemistry was described by T. Dubuffet, R. Sauvêtre and J. F. Normant, J. Organomet. Chem., 1988, 341, 11.
13. B. M. Trost and M. K. T. Mao, Tetrahedron Lett., 1980, 21, 3523.
14. An alternative preparation of the vinyl sulfide from vinylidene difluoride (HFC-1132a) was reported S. Piettre, C. Decock, R. Merenyi and H. G. Viehe, Tetrahedron, 1987, 43, 4309.
15. P. J. Crowley, J. A. Howarth, W. M. Owton, J. M. Percy and K. Stansfield, Tetrahedron Lett., 1996, 37, 5975.
16. J. Burdon, P. L. Coe, I. B. Haslock and R. L. Powell, Chem. Commun., 1996, 49.
17. D. Masure, C. Chuit, R. Sauvêtre and J. F. Normant, Synthesis, 1978, 458.