8
784
H. Firouzabadi et al. / Tetrahedron Letters 44 (2003) 8781–8785
2
4b
out than using molecular iodine. Therefore, we stud-
ied iodination with NaI. Surprisingly iodination pro-
ceeded well with some of the substrates in excellent
yields with high regioselectivity (Table 2, entries 1–3).
Iodination of toluene proceeded in quantitative yield to
give an isomer ratio (para/ortho) of 60/40 (Table 2,
entry 5). This method was not effective for the iodina-
tion of benzene, diphenyl ether, naphthalene, or 1-
methoxynaphthalene (Table 2, entries 6, 7, 8, 9).
Goto, R. Bull. Chem. Soc. Jpn. 1966, 39, 128; (d) Suzuki,
H. Bull. Chem. Soc. Jpn. 1970, 43, 481.
7. (a) Chaikovskii, V. K.; Novikov, A. N. Zh. Prikl. Khim.
1984, 57, 134; C. A. 1984, 100, 191452; (b) Chaikovskii,
V. K., Novikov, V. T., Novikov, A. N. Garifullina, F.
Sh. Zh. Obshch. Khim. 1985, 55, 893; Chem. Abstr. 1985,
103, 141534.
8. (a) Shimizu, A.; Yamataka, K.; Isoya, T. Bull. Chem.
Soc. Jpn. 1985, 58, 1611; (b) Lulinski, P.; Skulski, L. Bull.
Chem. Soc. Jpn. 1997, 70, 1665.
We have compared some of the results obtained by our
method for iodination of arenes with those reported
9. Himizu, A.; Yamataka, K.; Isoya, T. Bull. Chem. Soc.
Jpn. 1985, 58, 1611.
10. Krassowska-Swiebocka, B.; Lulinski, P.; Skulski, L. Syn-
thesis 1995, 926.
22,23
using NO gas and Silfen (Table 3).
2
During the course of this study we applied this reagent
system for the bromination of benzene, naphthalene
and their activated derivatives with molecular bromine
and NaBr (Scheme 1). In comparison to the iodina-
tion reactions, bromination proceeded well, usually in
excellent yields with faster reaction rates and higher
regioselectivity. The features of this bromination
method are: high yielding bromination of benzene,
highly regioselective bromination of 4-methoxytoluene,
diphenyl ether, naphthalene and 1-methoxynaphthalene
11. Bachki, A.; Foabelo, F.; Yus, M. Tetrahedron 1994, 50,
5139.
12. Ghalkorski, T. S.; Kharlova, V. D.; Filimonov; Sary-
acheva, T. A. Synthesis 1999, 5, 748.
13. Castanet, A.-S.; Colobert, F.; Broutin, P.-E. Tetrahedron
Lett. 1997, 43, 5047.
2
4
14. Sy, W.-W.; Lodge, B. A.; By, A. W. Synth. Commun.
1990, 6, 877.
15. Marko, Z.; Jerney, I.; Stogan, S. Tetrahedron Lett. 1997,
35, 6305.
(
see Table 4). Substitution of Br by NaBr makes the
16. (a) Carmen Carreno, M.; Garcia Ruano, J. L.; Sanz, G.;
Toledo, M. A.; Urbano, A. Tetrahedron Lett. 1996, 23,
4081; (b) Hajipour, A. R.; Arbabian, M.; Ruoho, A. E. J.
Org. Chem. 2002, 67, 8622.
2
protocol much easier, more economical and environ-
mentally favored.
In conclusion, we have provided a simple method for
the direct, regioselective iodination and bromination of
benzene, naphthalene and other activated aromatic
compounds using molecular iodine and bromine and
their sodium salts in the presence of the stable
Fe(NO ) 1.5N O /charcoal system.
17. (a) Firouzabadi, H.; Iranpoor, N.; Zolfigol, M. A. Synth.
Commun 1997, 27, 3301; (b) Firouzabadi, H.; Iranpoor,
N.; Zolfigol, M. A. Bull. Chem. Soc. Jpn. 1998, 71, 905.
Firouzabadi, H.; Iranpoor, N.; Zolfigol, M. A. Bull.
Chem. Soc. Jpn. 1998, 71, 2169; (c) Firouzabadi, H.;
Iranpoor, N.; Zolfigol, M. A. Synth. Commun. 1998, 28,
3
3
2
4
367; (d) Firouzabadi, H.; Iranpoor, N.; Zolfigol, M. A.
Synth. Commun. 1998, 28, 2773; (e) Zolfigol, M. A.;
Firouzabadi, H.; Iranpoor, N. Orient. J. Chem. 1998, 14,
3
69.
Acknowledgements
1
1
2
8. (a) Iranpoor, N.; Firouzabadi, H.; Heydari, R. Synth.
Commun. 1999, 19, 3295; (b) Iranpoor, N.; Firouzabadi,
H.; Heydari, R. J. Chem. Res. Synop. 1999, 11, 668.
9. (a) Iranpoor, N.; Firouzabadi, H.; Pourali, A. R. Tetra-
hedron 2002, 58, 5179; (b) Iranpoor, N.; Firouzabadi, H.;
Pourali, A. R. Synthesis 2003, 1591.
We thank Shiraz University Research Council for par-
tial support of this work.
0. Addison, C. C. Chem. Rev. 1980, 80, 21.
References
21. Active charcoal (2.5 g) was added to a solution of
Fe(NO ) ·1.5N O (5 g) in dry CH Cl (10 mL) at 0°C
3
3
2
4
2
2
1
2
. Merkushev, E. B. Synthesis 1988, 923.
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3
3
2
4
was stored in a capped bottle in the refrigerator.
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. (a) Abderrazak, B.; Francisco, F.; Miguel, Y. Tetra-
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4
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. March, J. Advanced Organic Chemistry, 4th ed.; Wiley-
Interscience: New York, 2000.
2
2
mmol) was added to the stirred mixture of Fe(NO ) ·1.5
3
3
. Morozov, S. V.; Shakirov, M. M.; Shubin, V. G. Zh.
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N O /charcoal (0.5 mmol) and I or Br (1.1 mmol) in
2 4 2 2
dry CH Cl2 (5 mL) at room temperature. After the
2
1
39.
appropriate time, the reaction mixture was filtered. To
the resulting filtrate, Na S O solution (10%, 10 mL) was
6
. (a) Wirth, H. O.; Konigstein, O.; Kern, W. Liebigs Ann.
Chem. 1977, 42, 4049; (b) Ahmed, S.; Razaq, S. Tetra-
hedron 1976, 32, 503; (c) Suzuki, H.; Nakamura, K.;
2
2
4
added and the mixture extracted with Et O (3×10 mL)
2
and dried over anhydrous Na SO . After filtration and
2
4