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4347
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In summary, we have developed a highly efficient meth-
od for preparation of 2-arylbenzothiazoles 2 and 2-benz-
oyl-benzothiazoles 4 using manganese(III)-promoted
radical cyclizations of arylthioformanilides 1 and a-benz-
oylthio-formanilides 3 under microwave irradiation.
´
´
13. Benedı, C.; Bravo, F.; Uriz, P.; Fernandez, E.; Claver, C.;
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Acknowledgements
We thank the Key Laboratory of Organic Synthesis of
Jiangsu Province and Suzhou Scientific Committee for
financial supports (JSK016 and SG 0219) and good sug-
gestions from Dr. Wei Zhang of Fluorous Technologies,
Inc., U-PARC 970 William Pitt Way, Pittsburgh, PA
15238, USA.
17. Lidstrom, P.; Tierney, J.; Wathey, B. Tetrahedron 2001,
57, 9225–9283.
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Supplementary data
22. Bush, J. B., Jr.; Finkbeiner, H. J. Am. Chem. Soc. 1968,
90, 5903.
Supplementary data associated with this article can be
23. General procedure for the preparation of 2-phenylbenzo-
thiazole (2a) using conventional heating: To a solution of
thiobenzanilide (1a) (0.21 g, 1 mmol) dissolved in 15 mL
acetic acid, was added Mn(OAc)3Æ2H2O (0.81 g, 3 mmol,
3 equiv), the mixture was stirred at 110 ꢁC for 6 h. Then
the mixture was allowed to cool to room temperature,
poured into water and extracted with chloroform for three
times (3 · 20 mL). The organic layer was dried over
anhydrous Na2SO4, filtered, concentrated and purified
by column chromatography on silica-gel using petroleum
ether/acetone = 4:1 as eluent to give 2-phenylbenzothiaz-
ole (2a), yield 60%.
24. General procedure for preparation of 2-phenylbenzothiaz-
ole (2a) under microwave irradiation: Into 100 mL three-
necked flask thiobenzanilide (1a) (0.21 g, 1 mmol) and
acetic acid (15 mL) were added. The flask was placed into
a microwave vessel, Mn(OAc)3Æ2H2O (0.81 g, 3 mmol,
3 equiv) was added. The mixture was heated to 110 ꢁC for
6 min at 300 W in a kitchen-type microwave oven. The
treatment and purification procedure of the mixture was
same as Ref. 23. Compound 2a, Yield 80%, mp 115–
116 ꢁC. 1H NMR(CDCl3): d 7.37–8.12 (m, 9H, C6H5,
C6H4); 13C NMR (CDCl3): d 168.5, 154.5, 135.4, 134.0,
131.4, 129.4, 128.0, 126.7, 125.6, 123.6, 122.0; HRMS: m/z
(%, elemental composition), calcd for C13H9NS (M+)
211.0456, found 211.0462 (M+, 100.0).
References and notes
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1
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