H. Chabane et al. / Tetrahedron Letters 43 (2002) 2483–2486
Table 1. Synthesis of the imines 9 and thermolysis results
2485
Starting material
R
Yield of 9 (%)
Yield of 10 (%)
Yield of 11 (%)
8aa
8bc
8cd
H
Et
50
70
70
n.d.b
12
15
5
38
45
(CH2)2CO2Et
a The synthesis of 8a involves nitration (HNO3/CH3COOH) of the carbazole (yield: 85%) and reduction of the nitro group (H2, Pd/C in ethyl
acetate) to give the corresponding amine (yield: 60%, see Refs 7b and 7c).
b n.d.: not detected.
c Commercially available.
d Prepared as described in Ref. 9.
derivative 10a was detected and a very low yield of the
angular product 11a was obtained. Yields of com-
pounds 9, 10 and 11 are listed in Table 1.
7. (a) Letois, B.; Lancelot, J. C.; Rault, S.; Robba, M.;
Tabka, T.; Gauduchon, P.; Bertreux, E.; Le Talaer, J. Y.
Eur. J. Med. Chem. 1990, 25, 775–784; (b) Tabka, T.;
He´ron, F.; Gauduchon, P.; Le Talaer, J. Y.; Lancelot, J.
C.; Rault, S.; Robba, M. Eur. J. Med. Chem. 1988, 23,
119–124; (c) Lamazzi, C. PhD Thesis, Universite´ d’Or-
le´ans, France, 1999.
In conclusion, we have described the synthesis of novel
polyheterocyclic systems, which are structurally very
close to the natural alkaloid ellipticine or pyridocarba-
zole congeners. In connection with our recently pub-
lished results,10 this work is a further example of the
utility of 4,5-dichloro-1,2,3-dithiazolium chloride in the
preparation of novel thiazolo heterocyclic systems.
Preparation of various substituted derivatives is under-
way and their biological evaluation11 will be described
later.
8. All compounds were fully characterised by spectroscopic
and elemental analysis.
Selected data for the new linear thiazolocarbazoles ana-
logues of ellipticine:
4,10-Dimethyl-9H-1-thia-3,9-diaza-cyclopenta[b]fluorene-
2-carbonitrile 7: A solution of the imino-1,2,3-dithiazole
6 (0.3 mmol) in diphenyl ether (2 mL) was heated under
argon at 200°C for 30 min. Purification by column chro-
matography (light petroleum/dichloromethane) afforded
the attempted product 7. Yellow needles, mp>260°C
(Found M+, 277.0677. C16H11N3S requires 277.0673);
wmax (KBr)/cm−1 3394, 3347, 2222 (CN), 1605, 1578, 1458,
1329, 1251, 1120; lH (400 MHz, DMSO-d6), 2.74 (s, 3H,
CH3), 3.21 (s, 3H, CH3), 7.28 (td, 1H, J=8.3 and 1.9 Hz,
Har), 7.52 (td, 1H, J=8.3 and 1.9 Hz, Har), 7.59 (d, 1H,
J=8.3 Hz, Har), 8.29 (d, 1H, J=8.3 Hz, Har), 11.67 (s,
1H, NH); lC (100 MHz, DMSO-d6) 15.5, 16.5, 108.9,
111.2, 114.1, 119.6, 122.9, 123.0, 123.1, 126.6, 126.8,
129.7, 133.6, 139.7, 141.4, 144.6; m/z 277 (M+, 100%),
262 (M+−CH3, 13). Anal. calcd for C16H11N3S: C, 69.29;
H, 3.99; N, 15.15. Found: C, 69.26; H 4.04; N 15.12.
Thiazolocarbazoles 10b and 10c; thermolysis general
procedure.
Acknowledgements
We thank Laboratoires SERVIER and the Comite´ de
Charente-Maritime de la Ligue Nationale contre le
Cancer for financial support.
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