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Scheme 2. ON/OFF light experiment.
A plausible reaction mechanism was outlined in Scheme 3.
Initially, 2-iminothiophenol
A
is generated from 2-
aminothiophenol and the aldehyde. Under photoirradiation, A is
oxidized by oxygen to produce 2,2’-iminodisulfide B. 2-
Iminophenylthily radial C is generated via light-promoted
homolysis of B. The intramolecular addition affords the radical
intermediate D, which is oxidized to give the final product E.
7.
8.
9.
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Scheme 3. Proposed reaction mechanism.
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In summary, we have developed a visible-light-promoted
synthesis of benzothiazoles from 2-aminothiophenols and
aldehydes. Aromatic, heteroaromatic and aliphatic aldehydes are
applicable in the transformation. The benzothiazole products
could be prepared in good yields. A radical reaction pathway via
the diaryl disulfide intermediates is proposed. The finding
provides an efficient and convenient synthetic approach to
benzothiazoles.
Acknowledgments
We thank the National Natural Science Foundation of China (no.
21472248) for the financial support of this study.
14. Hu, R.; Li, X.; Tong, Y.; Miao, D.; Pan, Q.; Jiang, Z.; Gan, H.; Han,
S. Synlett, 2016, 27, 1387.
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Supplementary Material
Supplementary data associated with this article can be found in
the online version, at http://. These data include experimental
1
procedure, characterization data of products, and copies of H,
13C NMR spectra.
17. Ye, L. M.; Qian, L.; Chen, Y. Y.; Zhang, X. J.; Yan, M. Org. Biomol.
Chem., 2016, ASAP (DOI: 10.1039/C6OB02461K).
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References and notes
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