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implies the use of CA under irradiation in a non-polar solvent
(Table 3).
In conclusion, for first time we have reported a photocyclization
of thioformanilines induced by chloranil in toluene at 80 °C, to af-
ford benzothiazole in moderate to good yields. The method is sim-
ple and the heterocycles are easily isolated from the reaction
mixture.
Acknowledgments
This work was supported in part by Consejo Nacional de Inves-
tigaciones Científicas y Técnicas (CONICET), Secretaría de Ciencia y
Tecnología (SECyT)-Universidad Nacional de Córdoba (UNC), and
Fondo para la Investigación Científica y Tecnológica (FONCyT).
V.R. gratefully acknowledges receipt of a fellowship from CONICET.
The authors thank Prof. S. Bertolotti for LFP facilities.
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Supplementary data
Laser flash photolysis spectra of CA and 1b in 1,2-dichloroeth-
ane, MeCN, and benzene, plot of 1/s against concentration of 1a
to obtain kq in MeCN (Figures S1, S2, S3, and S4). Supplementary
data associated with this article can be found, in the online version,
19. Del Giacco, T.; Elisei, F.; Lanzalunga, O. Phys. Chem. Chem. Phys. 2000, 2, 1701–
1708.
20. Oxidation potential versus SCE are given.
References and notes
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10 mL three-necked Schlenk tube, equipped with
a nitrogen gas inlet, a
condenser, and a magnetic stirrer. The tube was dried under vacuum, filled
with nitrogen, and then charged with dried 1,2-dichloroethane or toluene
(Method A or B, respectively) (4.0 mL). Thioanilide 1a (0.2 mmol) and CA
(0.2 mmol) were added to the degassed solvent under nitrogen and irradiated
for 3 h with a medium pressure Hg lamp emitting maximally at 365 nm at the
temperature indicated. After analyzing the reaction mixture by GC and GC–MS,
the solvent was evaporated and benzothiazole was isolated by radial or column
chromatography. The identity of all the products was confirmed by 1H and 13
C
NMR and MS spectrometry. All the benzothiazole compounds are known and
their data are in good agreement with those reported.
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26. The concentration of the reactant in Ref. 17a,b is not given.