reactor used: 10 and 70 ml) Prolabo microwave reactor (300 W,
monomode system) which has a quartz reactor, variable speed
rotation, visual control, irradiation (300 W) monitored by PC
computer, infrared measurement and continuous feedback
temperature control (by PC).5
Acknowledgements
We thank the Communauté de Villes de l’Agglomération de La
Rochelle (J. G. PhD grant), le Comité de Charente-Maritime
de la Ligue Nationale contre le Cancer and Prolabo (Merck
group) for financial support, the Royal Society of Chemistry
for the award of a Journals Grant to T. B., and the Wolfson
Foundation for establishing the Wolsfon Centre for Organic
Chemistry in Medical Science at Imperial College.
Typical procedure for the synthesis of 2-cyanobenzothiazoles
A stirred mixture of dithiazole 2 (1 mmol) and CuI (1.1 mmol)
was heated or irradiated in pyridine (10 ml) for the time shown
(Table 1). Dichloromethane (10 ml) was added and the organic
layer washed twice with a sodium thiosulfate solution (20%).
The crude product was purified by column chromatography on
silica gel with light petroleum–dichloromethane as the eluent.
No benzothiazole was formed in the absence of CuI.
Notes and references
† This work is a part of the PhD thesis of J. G. under the supervision of
T. B.
1 R. Appel, H. Janssen, M. Siray and F. Knoch, Chem. Ber., 1985, 118,
1632.
Selected data for new compounds
2 (a) T. Besson, K. Emayan and C. W. Rees, J. Chem. Soc., Perkin
Trans. 1, 1995, 2097; (b) O. A. Rakitin, C. W. Rees and O. G. Vlasova,
Tetrahedron Lett., 1996, 37, 4589; (c) T. Besson and C. W. Rees,
J. Chem. Soc., Perkin Trans. 1, 1996, 2857; (d) C. W. Rees, D. G.
Roe and V. Thiéry, Chem. Commun., 1996, 2775; (e) T. Besson,
G. Guillaumet, C. Lamazzi and C. W. Rees, Synlett, 1997, 704.
3 (a) C. W. Rees, J. Heterocycl. Chem., 1992, 29, 639; (b) T. Besson and
C. W. Rees, J. Chem. Soc., Perkin Trans. 1, 1995, 1659; (c) R. F.
English, O. A. Rakitin, C. W. Rees and O. G. Vlasova, J. Chem. Soc.,
Perkin Trans. 1, 1997, 201.
6-Methylbenzothiazole-2-carbonitrile 3c. White needles, mp
92 ЊC (from propan-2-ol) (Found: Mϩ, 174.0252. C9H6N2S
requires M, 174.0252); νmax(KBr)/cmϪ1 2940, 2228 (CN), 1607,
1560, 1474, 1316, 1244 and 816; δH (400 MHz, CDCl3) 7.46
(1H, dd, J 1.6 and 8.6 Hz, Harom), 7.76 (1H, d, J 1.6 Hz,
Harom), 8.10 (1H, d, J 8.6 Hz, Harom); δC (100 MHz, CDCl3)
21.81 (Me), 113.14 (CN), 121.21, 124.71, 129.79, 135.30,
135.69, 139.52 and 150.53; m/z 174 (Mϩ, 100%), 146 (3), 121
(18).
4 V. Bénéteau, T. Besson and C. W. Rees, Synth. Commun., 1997, 27,
2275.
5 (a) R. Commarmot, R. Didenot and J. F. Gardais, Rhône-Poulenc/
Prolabo, Patent 84/03496, 1984, Fr. Pat. FR 2560686, 1985; (b)
P. Jacquault, Prolabo, Fr. Pat. FR 9116286, 1991.
6 G. P. Ellis and T. M. Romney-Alexander, Chem. Rev., 1987, 87, 779.
7 T. Besson, M. J. Dozias, J. Guillard, P. Jacquault, M. D. Legoy and
C. W. Rees, Tetrahedron, 1998, 54, 6475; For reviews see: S. Caddick,
Tetrahedron, 1995, 51, 10403; K. Bougrin, M. Soufiaoui, A. Loupy
and P. Jacquault, New. J. Chem., 1995, 19, 213; S. A. Galema,
Chem. Soc. Rev., 1997, 26, 233.
5-Trifluoromethylbenzothiazole-2-carbonitrile 3e. White nee-
dles, mp 102 ЊC (from propan-2-ol) (Found: Mϩ, 277.9966.
C9H3N2SF3 requires M, 227.9969); νmax(KBr)/cmϪ1 3046, 2241
(CN), 1939, 1615, 1460, 1339, 1316, 1064 and 927; δH (400
MHz, CDCl3) 7.85 (1H, dd, J 1.2 and 8.6 Hz, Harom), 8.12
(1H, d, J 8.6 Hz, Harom), 8.49 (1H, s, Harom); δC (100 MHz,
CDCl3) 112.33 (CN), 122.66, 122.76, 123.52 (CF3), 124.88,
130.86, 138.38, 138.79 and 151.78; m/z 228 (Mϩ, 100%), 209
(10), 157 (18), 132 (15).
Communication 8/07899H
3926
J. Chem. Soc., Perkin Trans. 1, 1998, 3925–3926