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References and notes
10. Bhujanga Rao, A. K. K.; Gundu Rao, C.; Singh, B. B. J.
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1
1. Preparation of 2,4,5-tribromoimidazole 2a is given as a
1
. (a) Commercon, A.; Ponsonet, G. Tetrahedron Lett. 1990,
typical procedure for tribromination. Finely powdered
KHCO (30 g, 0.3 mol) was added to a solution of 1H-
3
3
1, 3871–3874; (b) Paris, J. M. Tetrahedron Lett. 1991, 32,
4
905–4906.
imidazole (6.8 g, 0.1 mol) in DMF (25 mL). The suspen-
sion was cooled to 0 °C and bromine (16 mL, 0.3 mol) was
added drop-wise during 1 h. The reaction medium was
heated to 100 °C and stirred for 2–3 h until completion of
the reaction (TLC). A yellow mixture was obtained. After
cooling, cold water (150 mL) was added and the precipi-
tate was washed with water, dissolved in NaOH (5%) and
treated by HCl (10%). After filtration and aqueous
washing until neutralization, the solid was dried yielding
2
3
4
5
. Anderson, W. K.; Bhattacharjee, D.; Houston, D. M. J.
Med. Chem. 1989, 32, 119–127.
. See for example, McReynolds, M. D.; Dougherty, J. M.;
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. For a review see: Wasserscheid, P.; Keim, W. Angew.
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. (a) Iddon, B. Heterocycles 1985, 23, 417–443; (b)
Iddon, B.; Khan, N. J. Chem. Soc., Perkin Trans. 1
1
987, 1445–1451, and 1453–1455; (c) Turner, R. M.;
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. Lipshutz, B. H.; Hagen, W. Tetrahedron Lett. 1992, 33,
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. (a) Light, L.; Pyman, F. L. J. Chem. Soc. 1922, 121, 2626–
1
3
1
9.5 g (64%) of 2a as a white powder. All products
1 13
obtained by this method were characterized by H,
C
5
NMR and melting points, which were found comparable
to those reported in the literature.
6
7
5
1
1
1
2. O’Connell, J. F.; Parquette, J.; Vell, W. E.; Wang, W.;
Rapoport, H. Synthesis 1988, 767–771.
3. Symons, M. C. R.; Bowman, W. R. J. Chem. Soc., Perkin
Trans. 2 1990, 975–979.
4. These conditions were also reported to be efficient for the
methylation of iodoimidazole. See Hoffer, M.; Toome, V.;
Brossi, A. J. Heterocycl. Chem. 1966, 3, 454–458.
2
1
630; (b) Balaban, I. E.; Pyman, F. L. J. Chem. Soc. 1924,
25, 1564–1572.
8
9
. Stensio, K. E.; Wahlberg, K.; Wahren, R. Acta Chem.
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. Iddon, B.; Lim, B. L. J. Chem. Soc., Perkin Trans. 1 1983,
7
35–739.