9842
Y. Chang et al. / Tetrahedron 64 (2008) 9837–9842
4.2.17. 1,2-Bis(3-bromophenyl)-1,1,2,2-tetrafluoroethane (7b)
Acknowledgements
White solid (45% yield). Mp: 105–107 ꢀC. 1H NMR (CDCl3)
d:
7.63–7.68 (m, 4H), 7.41–7.43 (m, 2H), 7.30–7.34 (m, 2H). 19F NMR
This work was supported by National Science Foundation
(CAREER DMR-0747667) and Department of Energy (DE-FG36-
05GO85028).
(CDCl3)
d
: ꢂ111.79 (s, CF2). 13C NMR (CDCl3)
d: 134.6, 132.6 (t,
2JCF¼25.3 Hz), 130.4 (t, JCF¼4.1 Hz), 130.1, 125.9 (t, JCF¼3.7 Hz),
122.6, 115.9 (tt, 1JCF¼253.0 Hz, 2JCF¼37.2 Hz). MS (EI) m/z: 412 (Mþ,
17%), 205 (100), 126 (63), 107 (10), 75 (17), 50 (11). HRMS (EI) calcd
for C14H8Br2F4 (Mþ) 409.8928, found 409.8928.
3
3
Supplementary data
Supplementary spectra (1H, 19F, and 13C NMR and MS) of all
products. Supplementary data associated with this article can be
4.2.18. 1,2-Bis(4-bromophenyl)-1,1,2,2-tetrafluoroethane (7c)
White solid (71% yield). Mp: 98–100 ꢀC. 1H NMR (CDCl3)
d: 7.58
(d, J¼8.6 Hz, 4H), 7.33 (d, J¼8.6 Hz, 4H). 19F NMR (CDCl3)
: ꢂ112.31
d
(s, CF2). 13C NMR (CDCl3)
d
: 131.8, 129.7 (t, 2JCF¼26.1 Hz), 128.9 (m),
126.2, 116.4 (tt, 1JCF¼252.3 Hz, 2JCF¼36.5 Hz). MS (EI) m/z: 412 (Mþ,
10%), 205 (100), 126 (60), 107 (10), 75 (15), 50 (12). HRMS (EI) calcd
for C14H8Br2F4 (Mþ) 409.8928, found 409.8939.
References and notes
1. (a) Chambers, R. D. Fluorine in Organic Chemistry; Blackwell: Oxford, 2004; (b)
Uneyama, K. Organofluorine Chemistry; Blackwell: Oxford, 2006; (c) Banks, R. E.;
Smart, B. E.; Tatlow, J. C. Organofluorine Chemistry, Principles and Commercial
Applications; Plenum: New York, NY, 1994; (d) Filler, R. In Organofluorine
Compounds in Medicinal and Biomedical Applications; Filler, R., Kobayashi, Y.,
Yagupolskii, L. M., Eds.; Elsevier Science: Amsterdam, 1993; (e) Preparation,
Properties, and Industrial Applications of Organofluorine Compounds; Banks, R. E.,
Ed.; Ellis Horwood: Chichester, West Sussex, UK, 1982; (f) Enantiocontrolled
Synthesis of Organo-Fluorine Compounds: Stereochemical Challenge and Bio-
medical Targets; Sholoshonok, V. A., Ed.; Wiley & Sons: New York, NY, 1999.
2. (a) Smith, W. C.; Tullock, C. W.; Muetterties, E. L.; Hasek, W. R.; Fawcett, F. S.;
Engelhardt, V. A.; Coffman, D. D. J. Am. Chem. Soc. 1959, 81, 3165–3166; (b)
Hasek, W. R.; Smith, W. C.; Engelhardt, V. A. J. Am. Chem. Soc. 1960, 82, 543–551;
(c) Boswell, G. A.; Ripka, W. C.; Scribner, R. M.; Tullock, C. W. Org. React. (N.Y.)
1974, 21, 20–30; (d) Gerstenburger, M. R. C.; Haas, A. Angew. Chem., Int. Ed. Engl.
1981, 20, 647–667; (e) Dmowski, W.; Kaminski, M. J. Fluorine Chem. 1983, 23,
219–228.
3. (a) Messina, P. A.; Mange, K. C.; Middleton, W. J. J. Fluorine Chem. 1989, 42, 137–
143; (b) McCarthy, J. R.; Peet, N. P.; LeTourneau, M. E.; Inbasekaran, M. J. Am.
Chem. Soc. 1985, 107, 735–737; (c) Manandhar, S.; Singh, R. P.; Eggers, G. V.;
Shreeve, J. M. J. Org. Chem. 2002, 67, 6415–6420; (d) Nishizono, N.; Sugo, M.;
Machica, M.; Oda, K. Tetrahedron 2007, 63, 11622–11625; (e) Robins, M. J.;
Wnuk, S. F. J. Org. Chem. 1993, 58, 3800–3801; (f) Middleton, W. J. J. Org. Chem.
1975, 40, 574–578; (g) Singh, R. P.; Shreeve, J. M. J. Org. Chem. 2003, 68, 6063–
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Org. Process Res. Dev. 2008, 12, 345–348.
4.2.19. 1,2-Bis(2-chlorophenyl)-1,1,2,2-tetrafluoroethane (7d)
White solid (22% yield). Mp: 104–106 ꢀC. 1H NMR (CDCl3)
d: 7.54
(d, J¼8.0 Hz, 2H), 7.38–7.44 (m, 4H), 7.29–7.33 (m, 2H). 19F NMR
(CDCl3)
d
: ꢂ107.34 (s, CF2). 13C NMR (CDCl3)
d: 133.7, 132.4, 132.0,
2
1
130.7 (m), 128.4 (t, JCF¼26.1 Hz), 126.6, 117.0 (tt, JCF¼255.7 Hz,
2JCF¼37.2 Hz). MS (EI) m/z: 322 (Mþ, 8%), 161 (100), 111 (6), 75 (23),
50 (5). HRMS (EI) calcd for C14H8Cl2F4 (Mþ) 321.9940, found
321.9932.
4.2.20. 1,2-Bis(3-chlorophenyl)-1,1,2,2-tetrafluoroethane (7e)
White solid (48% yield). Mp: 93–95 ꢀC. 1H NMR (CDCl3)
d: 7.48–
7.51 (m, 4H), 7.36–7.40 (m, 4H). 19F NMR (CDCl3)
d
: ꢂ118.81 (s, CF2).
13C NMR (CDCl3)
d
: 134.7, 132.5 (t, 2JCF¼25.3 Hz), 131.6, 129.8, 127.5
2
(m), 125.5 (m), 116.0 (tt, 1JCF¼252.7 Hz, JCF¼37.2 Hz). MS (EI) m/z:
322 (Mþ, 7%), 161 (100), 111 (9), 75 (11). HRMS (EI) calcd for
C
14H8Cl2F4 (Mþ) 321.9940, found 321.9928.
4.2.21. 1,2-Bis(4-chlorophenyl)-1,1,2,2-tetrafluoroethane (7f)
White solid (67% yield). Mp: 93–94 ꢀC. 1H NMR (CDCl3)
d: 7.38–
4. Lal, G. S.; Pez, G. P.; Pesaresi, R. J.; Prozonic, F. M. Chem. Commun. 1999, 215–216.
5. (a) Lal, G. S.; Pez, G. P.; Pesaresi, R. J.; Prozonic, F. M.; Cheng, H. J. Org. Chem.
1999, 64, 7048–7054; (b) Ye, C.; Shreeve, J. M. J. Fluorine Chem. 2004, 125, 1869–
1872; (c) Singh, R. P.; Shreeve, J. M. J. Fluorine Chem. 2002, 116, 23–26.
6. (a) Lal, G. S.; Lobach, E.; Evans, A. J. Org. Chem. 2000, 65, 4830–4832; (b) Singh,
R. P.; Twamley, B.; Shreeve, J. M. J. Org. Chem. 2002, 67, 1918–1924; (c) Singh, R.
P.; Chakraborty, D.; Shreeve, J. M. J. Fluorine Chem. 2001, 111, 153–160; (d) Singh,
R. P.; Majumder, U.; Shreeve, J. M. J. Org. Chem. 2001, 66, 6263–6267; (e) Singh,
R. P.; Shreeve, J. M. Org. Lett. 2001, 3, 2713–2715.
7.43 (m, 8H). 19F NMR (CDCl3)
d
: ꢂ112.15 (s, CF2). 13C NMR (CDCl3)
d:
2
137.8, 129.2 (t, JCF¼25.7 Hz), 128.8, 128.6 (m), 116.8 (tt,
2
1JCF¼252.9 Hz, JCF¼36.6 Hz). MS (EI) m/z: 322 (Mþ, 6%), 161 (100),
111 (8), 75 (9). HRMS (EI) calcd for C14H8Cl2F4 (Mþ) 321.9940, found
321.9949.
4.2.22. 1,2-Bis(4-fluorophenyl)-1,1,2,2-tetrafluoroethane (7g)8b
7. Mase, T.; Houpis, I. N.; Akao, A.; Dorziotis, I.; Emerson, K.; Hoang, T.; Iida, T.;
Itoh, T.; Kamei, K.; Kato, S.; Kato, Y.; Kawasaki, M.; Lang, F.; Lee, J.; Lynch, J.;
Maligres, P.; Molina, A.; Nemoto, T.; Okada, S.; Reamer, R.; Song, J. Z.; Tschaen,
D.; Wada, T.; Zewge, D.; Volante, R. P.; Reider, P. J.; Tomimoto, K. J. Org. Chem.
2001, 66, 6775–6786.
8. (a) Sondej, S. C.; Katzenellenbogen, J. A. J. Org. Chem. 1986, 51, 3508–3513; (b)
Charmbers, R. D.; Sandford, G.; Sparrowhawk, M. E.; Atherton, M. J. J. Chem. Soc.,
Perkin Trans. 1 1996, 1941–1944; (c) Motherwell, W. B.; Wilkinson, J. A. Synlett
1991, 191–192; (d) Prakash, G. K. S.; Hoole, D.; Reddy, V. P.; Olah, G. A. Synlett
1993, 691–693; (e) Kuroboshi, M.; Hiyama, T. Synlett 1991, 909–910; (f) Reddy,
V. P.; Alleti, R.; Perambuduru, M. K.; Welz-Biermann, U.; Buchholz, H.; Prakash,
G. K. S. Chem. Commun. 2005, 654–656.
9. (a) Bunnelle, W. H.; McKinnis, B. R.; Narayanan, B. A. J. Org. Chem. 1990, 55,
768–770; (b) Cava, M. P.; Levinson, M. I. Tetrahedron 1985, 41, 5061–5087.
10. Merrit, R. F. J. Org. Chem. 1967, 32, 4124–4126.
11. Zupan, M.; Pollak, A. J. Org. Chem. 1974, 39, 2646–2647.
12. Rozen, S.; Brand, M. J. Org. Chem. 1986, 51, 222–225.
White solid (92% yield). Mp: 99–100 ꢀC. 1H NMR (CDCl3)
d
: 7.43–
: ꢂ109.46 (s,
: 164.6 (d,
7.46 (m, 4H), 7.11 (t, J¼8.6 Hz, 4H). 19F NMR (CDCl3)
d
2F, Ar–F), ꢂ111.61 (s, 4F, CF2). 13C NMR (CDCl3)
d
1JCF¼250.1 Hz), 129.4 (m), 127.5 (t, JCF¼26.9 Hz), 116.5 (tt,
2
1JCF¼251.9 Hz, JCF¼36.8 Hz), 115.7 (d, JCF¼21.6 Hz). MS (EI) m/z:
2
2
290 (Mþ, 5%), 145 (100), 125 (3), 95 (10), 75 (6).
4.2.23. 1,2-Bis(4-methylphenyl)-1,1,2,2-tetrafluoroethane (7h)6d
White solid (86% yield). Mp: 137–140 ꢀC. 1H NMR (CDCl3)
d: 7.26
(d, J¼7.6 Hz, 4H), 7.11 (d, J¼7.6 Hz, 4H), 2.29 (s, 6H). 19F NMR (CDCl3)
d
: ꢂ111.84 (s, 2CF2). 13C NMR (CDCl3)
d: 141.3, 129.0, 128.3–128.6
1
2
(m), 127.1 (m), 117.1 (tt, JCF¼251.5 Hz, JCF¼36.5 Hz), 21.5. MS (EI)
13. York, C.; Prakash, G. K. S.; Olah, G. A. J. Org. Chem. 1994, 59, 6493–6494.
14. During the course of our study, we found a patent that described a direct
fluorination of benzophenone using 2,2-difluoro-1,3-dimethylimidazolidine
(U.S. Patent 6,329,529 B1, 2001). This reagent did not work for the fluorination
of benzil in our investigation, however.
m/z: 282 (Mþ, 10%), 141 (100), 101 (7), 91 (14).
4.2.24. 1,2-Bis(4-methoxyphenyl)-1,1,2,2-tetrafluoroethane (7i)
White solid (61% yield). Mp: 201–203 ꢀC. 1H NMR (CDCl3)
d: 7.34
15. When the crude reaction mixture from fluorination of 4,40-di-
chlorobenzophenone (4j) was checked using 19F NMR, two major signals in ad-
dition to the signal of 5j were observed: ꢂ132.1 ppm (br s) and ꢂ152.6 ppm (s) in
the integration ratio of 5:1. After aqueous workup, however, the fluorine signals
from the two by-products disappeared, and only the signal of 5j at ꢂ89.1 ppm (s)
remained. Based on this observation, we speculate that the fluorine-containing
by-products are hydrogen fluoride complexes of bis(methoxyethyl)amine.
(d, J¼8.8 Hz, 4H), 6.90 (d, J¼8.8 Hz, 4H), 3.84 (s, 6H).19F NMR (CDCl3)
d
: ꢂ111.49 (s, CF2).13C NMR (CDCl3): low solubility, only four kinds of
carbons were observed d: 161.6, 128.7 (m), 113.6, 55.6. MS (EI) m/z:
314 (Mþ, 8%), 157 (100), 114 (17), 109 (8). HRMS (EI) calcd for
16H14F4O2 (Mþ) 314.0930, found 314.0929.
C